Automated Radar Data Labeling using MoveNet for Human Gesture Recognition - Maiwald, Timo; Gabsteiger, Jasmin; Weigel, Robert; Lurz, Fabian (2023 Asia-Pacific Microwave Conference (APMC), 2024)
Integrated radar sensors constitute an emerging technology used from smart home to autonomous driving applications. In combination with machine learning for radar data signal processing, they experience increasing popularity and are heavily investigated. These methods however need huge amounts of labeled training data to perform well in realistic scenarios, which is time consuming and cost intensive. To increase data acquisition speed, this paper presents a system using a fast computer vision model for automated radar data labeling. It is capable of generating 10 labeled radar data frames per second. To demonstrate the abilities it is used for human gesture recognition.<br
Keywords: gesture recognition; fmcw radar; computer vision; machine learning

Automatically Adjustable Real-Time Capable Noise Filtering in Image Processing - Gabiger-Rose, Anna; Kube, Matthias; Schmitt, Peter; Weigel, Robert (Embedded World, 2011)
In this work, a way to achieve the best noise suppression in images while preserving the spatial resolution is presented. The noise filtering is done by means of a bilateral filter. The denotation bilateral filtering suggests the combination of domain and range filtering. The domain filter averages the nearby pixel values and acts thereby as a low-pass filter. The range filter stands for the nonlinear component and plays an important part in edge preserving. Both filtering components can be adjusted by according parameters. In this work the way is presented, how the adjustment parameter for the nonlinear photometric component of the filter can be derived from the noise standard deviation, which allows the highest PSNR increase while retaining the structural similarity index at high level. The noise statistics is measured during the initialization of the camera and stored for the filtering purpose. Using the presented instruction for the calculation of the adjustment parameter of the photometric component an automatical adjustment of the noise filter is possible, whereas the adjustment can be done for any noise standard deviation. It is shown, that utilizing the instruction for the automatical adjustment of the noise filter the noise suppression without a loss of structural information is achievable at any noise level.
elib2cris::1512001600,gabiger-rose2011

Automatic Communication Standard Recognition in Wireless Smart Home Networks - Kuba, Matthias; Klatt, M.; Ronge, Karlheinz; Weigel, Robert (IEEE Consumer Communications and Networking Conference (CCNC), 2012, 2012)
Automatic recognition of communication standards is a crucial task, if universal interoperability between different communication systems is claimed. A gateway performing the recognition task can be used to interconnect heterogeneous systems with different and incompatible protocol waveforms. This paper proposes an algorithm for the automatic recognition of various communication standards used for wireless smart home networks in the European 868 MHz Short-Range Device frequency band. Relevant statistical key features are extracted from the received signal and the recognition is based on threshold comparison. The algorithm is appropriate for the implementation in low-complexity embedded systems and works over a wide range of signal-to-noise ratios (SNR).
elib2cris::1512001600,kuba2012
Keywords: embedded systems; feature extraction; home networks; internetworking; network servers; open systems; protocols; radio networks

Automatic identification of wavelength range of VCSEL-based gas sensor using ratios of gas absorption lines - Hartmann, Alexander; Strzoda, Rainer; Weigel, Robert (Applied Physics B-Lasers and Optics, 2013)
In this paper a method for identifying the wavelength range of a tunable vertical cavity surface-emitting laser (VCSEL) is introduced. The measuring technology is wavelength modulation spectroscopy (WMS). The laser is tuned over its wavelength by applying a temperature ramp using the onboard Peltier element. During this ramp the 2f absorption lines are recorded. After finishing the temperature ramp and collecting the lines, a ratio-compare algorithm calculates the theoretical amplitudes of selected predefined lines. Then it compares the measured 2f line amplitudes iteratively with the theoretical ones. If the error of the ratios of the calculated and the measured lines is below a predefined limit, the searched lines and hence the emission wavelength are identified.
elib2cris::1512001600,hartmann2012

Automatic Signal Quality Index Determination of Radar-Recorded Heart Sound Signals Using Ensemble Classification - Shi, Kilin; Schellenberger, Sven; Michler, Fabian; Steigleder, Tobias; Malessa, Anke; Lurz, Fabian; Ostgathe, Christoph; Weigel, Robert; Kölpin, Alexander (IEEE Transactions on Biomedical Engineering, 2019)
Objective: Radar technology promises to be a touchless and thereby burden-free method for continuous heart sound monitoring which can be used to detect cardiovascular diseases. However, the first and most crucial step is to differentiate between high- and low-quality segments in a recording to assess their suitability for a subsequent automated analysis. This paper gives a comprehensive study on this task and firstly addresses the specific characteristics of radar-recorded heart sound signals. Methods: To gather heart sound signals recorded from radar, a bistatic radar system was built and installed at the university hospital. Under medical supervision, heart sound data were recorded from 30 healthy test subjects. The signals were segmented and labeled as high- or low-quality by a medical expert. Different state-of-the-art pattern classification algorithms were evaluated for the task of automated signal quality determination and the most promising one was optimized and evaluated using leave-one-subject-out cross-validation. Results: The proposed classifier is able to achieve an accuracy of up to 96.36% and demonstrates a superior classification performance compared to the stateof- the-art classifier with a maximum accuracy of 76.00 %. Conclusion: This paper introduces an ensemble classifier that is able to perform automated signal quality determination of radar-recorded heart sound signals with a high accuracy. Significance: Besides achieving a higher performance compared to state-of-the-art classifiers, the presented study is the first one to deal with the quality determination of heart sounds that are recorded by radar systems. The proposed method enables contactless and continuous heart sound monitoring for the detection of cardiovascular diseases.<br
Keywords: biomedical engineering; biomedical informatics; biomedical signal processing; heart sounds; medical radar; pattern recognition; phonocardiography

Automatische Erkennung von Kommunikationsstandards im Sub-GHz-Bereich - Kuba, Matthias; Oeder, Andreas; Ronge, Karlheinz; Weigel, Robert (RADCOM 2013, 2013)
Fuer die drahtlose Kommunikation im Heimautomatisierungsbereich wird im europae- ischen Raum bevorzugt das lizenzfrei verfuegbare 868 MHz Short Range Device Band eingesetzt. Haeufig verwenden Geraete unterschiedlicher Hersteller jedoch verschiedene Kommunikationsstandards und sind somit nicht in der Lage, Daten untereinander auszutauschen. Eine Loesung für dieses Problem bietet ein Funkgateway, das die Datenpakete zwischen den einzelnen Standards uebersetzt. Ist dieses Gateway zudem in der Lage, den verwendeten Kommunikationsstandard eines empfangenen Signals automatisch zu erkennen und den Empfaenger adaptiv auf diesen anzupassen, so laesst sich universelle Interoperabilitaet zwischen verschiedenen Technologien erreichen. In diesem Vortrag wird ein solches automatisches Erkennungsverfahren fuer einige im 868 MHz Band häufig vorkommende Standards vorgestellt. Zunaechst werden die Details des mustererkennungsbasierten Algorithmus dargelegt. Hiernach werden die Ergebnisse sowohl der simulativen als auch der messtechnischen Verifikation praesentiert und es erfolgt ein Vergleich der Ergebnisse aus Simulation und Messung. Schließlich werden einige moegliche Anwendungsszenarien fuer das vorgestellte Verfahren beschrieben.
elib2cris::1512001600,kuba2013

Automatische Klassifikation von Kommunikationsstandards im europäischen 868 MHz Short Range Device-Band - Kuba, Matthias (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2012)

Automatization of the storing-in part of a hydrogen storage system using Liquid Organic Hydrogen Carriers - Milella, Vito-Oronzo; Kölpin, Alexander; Schlücker, Eberhard (Energy Technology, 2017)
Accumulating electrical energy in decentralized electrical grids is a demanding task. Preliminary works exist on charging and discharging Liquid Organic Hydrogen Carriers (LOHC). These carriers allow for storage of hydrogen by reversible hydrogenation of an aromatic compound. A challenge is the fact that the chemical process has to be conducted within the power generating infrastructure, therefore a continuous and fully automatized implementation is mandatory. In this work the fundamentals of the control and automatization of LOHC based energy storage systems is presented. For this purpose the identification of the controlled variable is done, before determining their influence on the reaction dynamics. This concludes to a fully automatized hydrogenation process whereby the conductibility of the reaction, the performance and the necessity of applying safe and functional operation modes, are shown. Derived from that, the investigations will help establishing LOHC as feasible hydrogen carriers and doing a decisive step to mid and long term energy storage systems suitable to a modern smart grid infrastructure.
Keywords: LOHC

Automotive meets Adaptive Wireless Communication - Franchi, Norman; Spiteller, Florian; Weigel, Robert (4. GMM-Fachtagung Automotive meets Electronics (AmE), 2013)
Die Einbindung drahtloser Technologien in Fahrzeuge wird in den kommenden Jahren zunehmend an Bedeutung gewinnen. Die Vernetzung des Automobils mit mobilen Endgeräten der Passagiere sowie mit anderen Fahrzeugen und der Umwelt wird dabei als neue Schlüsselkompetenz für zukünftige Fahrzeugtechnik gesehen. In der Automotive-Branche werden bisher meist dedizierte Systeme mit integrierten Chiplösungen eingesetzt, deren Funktionen kaum dynamisch angepasst werden können. In diesem Beitrag wird daher ein modulares Konzept vorgestellt, das auf dem Software-Defined-Radio-Prinzip aufsetzt und großes Potential für die Entwicklung adaptiver und kosteneffizienter Umsetzungsformen von sog. Wireless Vehicular Communication Systems bietet. Mit Hilfe der exemplarischen Umsetzung eines neuartigen Prototyping-Ansatzes werden – am Beispiel der beiden automotive-relevanten Funkstandards IEEE 802.11bTM und IEEE 802.11pTM – sowohl die Stärken des Ansatzes selbst als auch der SDR-basierten Realisierungsform von flexiblen Funksystemen verdeutlicht.
elib2cris::1512001600,franchi2013
Keywords: Software Defined Radio; Wireless Vehicular Communication Systems; Rapid-SDR-Prototyping; IEEE 802.11p; IEEE 802.11b; USRP

Automotive Radar Interference Mitigation using a Convolutional Autoencoder - Fuchs, Jonas; Dubey, Anand; Lübke, Maximilian; Weigel, Robert; Lurz, Fabian (2020 International Conference on Radar (RADAR), 2020)
Automotive radar interference imposes big challenges on signal processing algorithms as it raises the noise floor and consequently lowers the detection probability. With limited frequency bands and increasing number of sensors per car, avoidance techniques such as frequency hopping or beamforming quickly become insufficient. Detect-and-repair strategies have been studied intensively for the automotive field, to reconstruct the affected signal samples. However depending on the type of interference, reconstruction of the time domain signals is a highly non-trivial task, which can affect following signal processing modules. In this work an autoencoder based convolutional neural network is proposed to perform image based denoising. Interference mitigation is phrased as a denoising task directly on the range-Doppler spectrum. The neural networks shows significant improvement with respect to signal-to-noise-plus-interference ratio in comparison to other state-of-the-art mitigation techniques, while better preserving phase information of the spectrum compared to other technique

A VCO with Wide Tuning Range and Output Switch for Pulsed Frequency Modulated UWB Signal Generation - Weigel, Robert; Eßwein, Alexander (German Microwave Conference, 2011)
This paper describes a VCO with 30% tuning range and integrated output switch, used for the generation of pulsed ultra-wideband signals in an FMCW radar system. The system concept is shown. The VCO with switch has an unmatched single-endedly measured output power of -21 dBm over the whole tuning range of 6.4 GHz to 8.6 GHz with a total of 31.8 mA bias current consumption.
elib2cris::1512001600,weigel2011a
Keywords: BiCMOS integrated circuits; CW radar; FM radar; MMIC; FMCW radar system; pulsed ultrawideband signal

A Versatile 10–80-Gb/s PRBS-Based Broadband Transmitter With Arbitrary 20–60-GHz Spectrum Shifting - Gharib, Ahmed; Weigel, Robert; Kissinger, Dietmar (IEEE Transactions on Microwave Theory and Techniques, 2016)

A Versatile Built-In Test Architecture for Integrated Millimeter-Wave Radar Receiver Front-Ends - Kissinger, Dietmar; Agethen, Roman; Weigel, Robert (IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2012, 2012)
This paper presents a versatile direct built-in test architecture for integrated radar receiver front-ends. It is used for determination of the gain and noise figure of a direct down-conversion receiver. The general test structure is introduced and a detailed analysis of different approaches for the test signal injection and calibration are given.
elib2cris::1512001600,kissinger2012b
Keywords: built-in self test; millimetre wave radar; radar receivers; built-in test architecture; direct down-conversion receiver; integrated millimeter-wave radar receiver front-end; millimeter wave; Noise measurement

A Versatile System Simulation Environment for Millimeter-Wave Phased-Array FMCW-Radar Sensors for Automotive Applications - Dudek, Manuel; Kissinger, Dietmar; Weigel, Robert; Fischer, Georg (Asia-Pacific Microwave Conference (APMC), 2011)
In this contribution a versatile system simulation environment for radar sensors being developed to operate in the automotive area is introduced. It combines a frontend simulation engine that is coupled in a co-simulation with a 3D ray-tracing tool to take the effects of the automotive radar channel into account, thus providing accurate and reliable results concerning the behavior of the implemented circuits in certain traffic situations. With respect to the latest developments in automotive radar, i.e. the transition from former comfort systems to current systems including an increased number of safety functions, the system simulation environment has been extended to support investigations on the phased-array radar principle. Applying this technique in the automotive area promises advantages in target detection in the vehicles vicinity by the means of increased hardware requirements, resulting in radar systems that are by far more difficult to design due to the number of side-effects that have to be additionally considered during the development process. To demonstrate the capability of this advanced simulation approach a typical traffic scenario is calculated showing not only the advantages of phased-array radar for the automotive field but also the performance of the simulation environment built up.
elib2cris::1512001600,dudek2011f

A Versatile, Voltage-Pulse Based Read and Programming Circuit for Multi-Level RRAM Cells - Pechmann, Stefan; Mai, Timo; Völkel, Matthias; Mahadevaiah, Mamathamba K; Perez, Eduardo; Quesada, Emilio Perez-Bosch; Reichenbach, Marc; Wenger, Christian; Hagelauer, Amelie (Electronics, 2021)
In this work, we present an integrated read and programming circuit for Resistive Random Access Memory (RRAM) cells. Since there are a lot of different RRAM technologies in research and the process variations of this new memory technology often spread over a wide range of electrical properties, the proposed circuit focuses on versatility in order to be adaptable to different cell properties. The circuit is suitable for both read and programming operations based on voltage pulses of flexible length and height. The implemented read method is based on evaluating the voltage drop over a measurement resistor and can distinguish up to eight different states, which are coded in binary, thereby realizing a digitization of the analog memory value. The circuit was fabricated in the 130 nm CMOS process line of IHP. The simulations were done using a physics-based, multi-level RRAM model. The measurement results prove the functionality of the read circuit and the programming system and demonstrate that the read system can distinguish up to eight different states with an overall resistance ratio of 7.9. <br
Keywords: analog circuit; memory programming; programming circuit; read circuit; resistive memory; RRAM; voltage pulse

A W-CDMA Zero-IF Front-End for UMTS in a 75 GHz SiGe BiCMOS Technology - Pretl, Harald; Schelmbauer, Werner; Maurer, Linus; Westermayr, H.; Weigel, Robert; Klepser, Bernd-Ulrich; Adler, Bernd; Fenk, K. (IEEE Radio Frequency Integrated Circuits Symposium, 2001)
A zero-IF front-end consisting of an I/Q down-conversion mixer, broadband I/Q-generation, fully-integrated VCO, dual-modulus prescaler, low-noise baseband buffer and blocking filter is presented. Integrated in a 75 GHz ft BiCMOS technology with 0.35 μm CMOS it draws 33 mA from a 2.7 V supply. Extremely low local-oscillator leakage of -95 dBm together with a high IIP2 of 55 dBm results in very low DC offset values of less than 20 mV at the baseband output of the IC. The presented circuit is intended for application in a highly-integrated UMTS receiver.
elib2cris::1512001600,pretl2001
Keywords: W-CDMA; Zero-IF Front-End; UMTS; SiGe BiCMOS

A Wideband Crosscorrelation Technique for High Precision Time Delay Estimation of Frequency Hopping GSM Signals - Götz, Alexander; Rose, Richard; Zorn, Stefan; Fischer, Georg; Weigel, Robert (European Microwave Conference (EuMC), 2011)
In this paper, a novel wideband crosscorrelation technique for high precision time delay estimation of frequency hopping GSM signals is presented. The technique makes use of the increased bandwidth of frequency hopping waveforms and acquires and processes the signals in a coherent way. This way, the actual applicable bandwidth for time delay estimation and localization purposes is increased significantly. In case of E-GSM 900 systems, up to 35 MHz of bandwidth can be used which enables localization of mobile phones in the order of a few meters. The technique is therefore ideally suited for search and rescue applications. The presented method may also be applied to TETRA, DECT, IEEE 802.15.4 (ZigBee) or IEEE 802.15.1 (Bluetooth) signals.
elib2cris::1512001600,goetz2011a
Keywords: GSM; TDOA; Localization; Frequency Hopping

A Wideband Scalar Network Analyzer for Biomedical Dehydration Measurements - Hofmann, Maximilian; Nehring, Johannes; Weigel, Robert; Fischer, Georg; Kissinger, Dietmar (IEEE Engineering in Medicine and Biology Conference (EMBC), 2013)
This paper presents a wideband microwave ap- proach towards biomedical dehydration monitoring. The intro- duced concept is verified via invasive measurements on several blood samples. A microwave measurement circuit, based of a two-port scalar vector network analyzer is presented. The circuit operates between 5GHz and 20GHz using a planar permittivity sensor. Measurements of all subcomponents are shown together with measurements of a Water-NaCl-Glycerol solution.
elib2cris::1512001600,hofmann2013d

A Wideband Unidirectional Antenna Array Element With Stable Radiation Pattern - Gardill, Markus; Weigel, Robert; Kölpin, Alexander (IEEE Topical Conference on Antennas and Propagation in Wireless Communications, 2012)
modification of the famous Bow Tie antenna element for wideband Direction-Of-Arrival estimation antenna arrays is designed. A constant input impedance as well as a very stable radiation pattern over a 37% bandwidth from 5.5 GHz to 8 GHz is achieved. In addition the proposed design uses a double layer substrate and hence allows for direct integration of the feed network and analog RF circuitry directly into the antenna array. The particular design is suited for low-cost integration and optimized for a wireless high-precision localization system.
elib2cris::1512001600,gardill2012a

A Wide-Range 77 GHz Direction of Arrival Detector with Integrated Dual Six-Port Receiver - Vinci, Gabor; Barbon, Francesco; Lämmle, Benjamin; Weigel, Robert; Kölpin, Alexander (International Microwave Symposium (IMS) 2012, 2012)
The six-port Direction Of Arrival (DOA) detector has opened a whole new set of possibilities and implementations for novel industrial sensors and radar applications. Detection ambiguity issues as well as challenging calibration techniques are still the main problems of this technology. In this paper the design of an innovative DOA detector system is presented, addressing especially solutions to the problems mentioned above. The proposed device works at 77 GHz and features an integrated Silicon-Germanium (SiGe) dual six-port receiver. Design issues are addressed as well as an overview of the DOA detector system. The highlights are high accuracy, wide range of DOA detection with no ambiguity issues, flexibility, low-complexity and low-cost.
elib2cris::1512001600,vinci2012d
Keywords: Calibration; Detectors; Microwave Circuits; Receiving Antennas; Silicon Germanium; Six-Port

A Wide-Tunable 20 GHz Differential Oscillator with Integrated Stripline Resonator in SiGe Bipolar Technology - Ettinger, Klaus; Bergmayr, M.; Fenk, Josef; Weigel, Robert (IEEE Bipolar/BiCMOS Circuits and Technology Meeting, 2000)
elib2cris::1512001600,ettinger2000

A wide tuning range high output power 56-74 GHz VCO with on-chip transformer load in SiGe technology - Nasr, Ismail; Lämmle, Benjamin; Knapp, Herbert; Fischer, Georg; Weigel, Robert; Kissinger, Dietmar (IEEE Topical Meeting Silicon Monolithic Integrated Circuits in RF Systems Digest, 2012)
This paper presents a wide tuning range modified Colpitts VCO with high output power. The circuit was fabricated using a lowcost SiGe technology with an ft/fmax of 170/250 GHz. The VCO can be tuned between 56.4 and 73.8 GHz having a tuning range of approx. 27%. The maximum measured output power is +9.4 dBm, and the output power remains above +7.0 dBm over the entire tuning range. The VCO has a minimum phase noise of -95 dBc/Hz, which stays below -88 dBc/Hz over the entire tuning range. On-chip frequency dividers were used to enable easier measurement. A single transformer was designed and used simultaneously for output matching of the VCO and as an output balun. The overall chip draws 112 mA from a 3.3 V supply, where the VCO draws 45 mA of the total current.
elib2cris::1512001600,nasr2012
Keywords: VCO; Transformer; Frequency Dividers; Colpitts; FMCW

A wireless AQP pressure sensor using chirped SAW delay lines structures - Reindl, Leonhard; Ruppel, Clemens; Riek, K.; Pankratz, Thomas; Weigel, Robert (Proceedings of IEEE Ultrasonics Symposium, 1998)
We report of the design of a SAW delay line developed for a wireless pressure sensing system operating in the 434 MHz ISM-band. The structure is a one port configuration fabricated on quartz 37.5°rotYX. It is hermetically sealed in all-quartz-package (APQ) technology with the SAW structure being placed on a diaphragm inside the cavity. The sensor allows for the measurement of absolute pressure values in the range from 0 to 8.5 bar. The SAW structure shows a linear phase although it incorporates chirped SAW components for enhancing the sensor sensitivity. The SAW structure is built up of two overlap-weighted dispersive split finger interdigital transducers (IDTs). An improvement of the sensor sensitivity by a factor of 32 compared to systems using non-dispersive SAW components has been achieved
elib2cris::1512001600,reindl1998a

A Wireless Joint Communication and Localization EMG-Sensing Concept for Movement Disorder Assessment - Brückner, Stefan; Weber, Jasmin; Michler, Fabian; Shanin, Nikita; Schober, Robert; Hagelauer, Amelie; Weigel, Robert; Gaßner, Heiko; Winkler, Jürgen; Eskofier, Björn; Vossiek, Martin (IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology, 2023)
Real-time sensory recording of the musculoskeletal system function is an important tool for the diagnosis, treatment planning, and optimal treatment execution of diseases, such as Parkinson's disease and osteoarthritis. This article presents a new wireless joint communication and localization electromyography (EMG)-sensing concept. An on-body sensor beacon measures EMG signals and wirelessly transmits them. At the same time, the spatial position and movement of the beacon is determined with high precision in real time using these transmitted radio signals. The seamless integration of multiple sensors avoids the need to synchronize and individually set up multiple independently operating sensors. An outstanding feature of the radio localization approach is that it does not require proprietary ultra-wideband signals or complicated time synchronization protocols, allowing for small and energy-efficient implementation. To demonstrate this novel concept, a wireless 3D-localizable EMG sensor was developed and experimentally evaluated. This new type of sensing concept allows, for the first time, the time-synchronous measurement of muscle activity and the underlying movement of the associated body part. URL: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10286030&isnumber=8000303<br
Keywords: Array signal processing; EMG; localization; radar tracking; radio communication

A Wireless Lightweight System Node for Energy Efficient Beehive Sensing - Kurin, Thomas; Horlbeck, Marie; Maiwald, Timo; Weigel, Robert; Lurz, Fabian (2023 IEEE Topical Conference on Wireless Sensors and Sensor Networks, WiSNeT 2023, 2023)
This paper discusses a novel ultra low power sensor system for monitoring a beehives' health condition, which can be determined by measuring internal temperature and humidity variations. It comprises an autonomous battery powered sensor node which transmits the measured data over a 868 MHz wireless radio link. Expected runtime is greater than 2.1 years.
CRIS-Team Scopus Importer:2023-03-17
Keywords: beehive; ultra low power; WSN

A Wireless Pressure-Measurement System Based on SAW Transponder Technique - Schimetta, Gernot; Dollinger, Franz; Springer, Andreas; Weigel, Robert (International Conference on Microwave, Radar and Wireless Communications, 2000)
elib2cris::1512001600,schimetta2000a

A Wireless Pressure Measurement System Using a SAW Hybrid Sensor - Schimetta, Gernot; Dollinger, Franz; Weigel, Robert (IEEE MTT-S Microwave Symposium, 2000)
A pressure-measurement system based on surface-acoustic-wave (SAW) sensors is presented in this paper. Since SAW sensors are powered by the energy of the RF field, no battery is required, which is a major drawback of conventional microcontroller-based telemetry systems. A successful combination of a SAW reflective delay line with a high-Q capacitive pressure sensor is shown, With a new way of matching the sensor impedance to the SAW reflector impedance, both a high signal-to-noise ratio and a high signal dynamic are achieved, which supports accurate signal evaluation. As an example of realization, the prototype of the pressure sensor unit is presented
elib2cris::1512001600,schimetta2000
Keywords: SAW; Sensor

A Wireless Spread Spectrum Communication System Using SAW Chirped Delay Lines - Springer, Andreas; Gugler, Wolfgang; Huemer, Mario; Koller, Rainer; Weigel, Robert (IEEE Transactions on Microwave Theory and Techniques, 2001)
We report on the use of broad-band chirp signals for spread-spectrum communications in indoor and industrial environments. The well-known pulse compression technique associated with chirp signals is exploited to achieve a highly robust communication system. For the generation and compression of the chirp signals, surface acoustic wave delay lines fabricated from an LiTaO3-X112rotY substrate are used. Center frequency, bandwidth, chirp duration, and chirp rate are 348.8 MHz, 80 MHz, 500 ns, and ±40 MHz/μs, respectively. Different modulation schemes for chirp signals are introduced, the effects of nonlinearities, frequency drift, and temperature drift are addressed, and simulations and measurement results from a hardware demonstrator are presented for the use of π/4-differential quadrature phase-shift keying (DQPSK) modulation. A data rate of up to 40 Mb/s has been achieved experimentally and shows that the proposed system is highly robust against multipath effects
elib2cris::1512001600,springer2001a
Keywords: Wireless communication; Surface acoustic waves; Spread spectrum communication; Signal generators; Pulse compression methods; Robustness; Frequency; Phase modulation; Chirp modulation; Communication industry

A X-coupled differential single-opamp resonator for low power continuous time Sigma-Delta-ADCs - Zeller, Sebastian; Münker, Christian; Weigel, Robert (Conference on Ph.D. Research in Microelectronics and Electronics, 2011)
Continuous time sigma-delta ADCs usually are designed with noise transfer functions containing conjugate complex zeros to extend the usable bandwidth. Traditionally, these zeros are implemented with a resonance generated by local feedback around two integrators. Recently a loop filter topology with reduced number of opamps based on modified Twin-T single-opamp resonators has been proposed with the aim to reduce power dissipation. In this work, we propose an alternative differential single opamp resonator with cross-coupled feedback, which is more compact, more power efficient, more robust to parasitics and more linear than the Twin-T based single-opamp resonators.
elib2cris::1512001600,zeller2011
Keywords: differential amplifiers; feedback amplifiers; low-power electronics; operational amplifiers; resonator filters; sigma-delta modulation

Bare Die Connections via Aerosol Jet Technology for Millimeter Wave Applications - Röhrl, Franz Xaver; Jakob, Johannes; Bogner, Werner; Weigel, Robert; Zorn, Stefan (European Microwave Conference, 2018)
This paper presents a comparison of chip connections using Aerosol Jet (AJ) and Bond technology on low cost PCB substrates. First, the behavior of the used gap filler material and the used silver ink on printed circuit boards are characterized. In addition to comparing the RF performance (DC to 67 GHz) of the two technologies, the mechanical stability is also compared. While the AJ technology transitions score above all for their RF performance and the lower requirements (surface finish, pad size and adhesion) on the PCB, the bonding technology has clear advantages, especially with different coefficient of thermal expansion (CTE) values of the substrates to be connected. Finally, the measurement results of a complete package are shown, whereby the chip connection is realized once by means of aerosol jet and once by bonding wire
Keywords: Aerosol jet technology; chip connection; bare die connection; organic chip package; RF package; impedance controlled PCB; millimeter wave; wideband package

Bare die connections via aerosol jet technology for millimeter wave applications - Röhrl, Franz Xaver; Jakob, Johannes; Bogner, Werner; Weigel, Robert; Zorn, Stefan (International Journal of Microwave and Wireless Technologies, 2019)
This paper presents a comparison of chip connections using aerosol jet (AJ) and bond technology on low-cost printed circuit board (PCB) substrates. First, the behavior of the used gap filler material and the used silver ink for AJ technology on PCBs are characterized. In addition to comparing the radio frequency (RF) performance (DC to 67 GHz) of the two technologies, the mechanical stability is also compared. While the AJ technology transitions score above all for their RF performance and the lower requirements (surface finish, pad size, and adhesion) on the PCB, the bonding technology has clear advantages, especially with a different coefficient of thermal expansion values of the substrates to be connected. Finally, the measurement results of a complete package are shown, whereby the chip connection is realized once by means of AJ and once by bonding wires.
CRIS-Team Scopus Importer:2019-07-02
Keywords: additive manufacturing; Aerosol jet technology; bare die connection; bond transitions; inkjet; millimeter wave

Baseband Architecture Design of Massive MIMO Communication System with FPGAs - Ali, Arslan (26th Meeting of ITG Professional Group for Applied Information Theory on Massive MIMO Theory and Applications, 2015)

Baseband Signal Processing for Wireless Sensor Nodes with Capability of FMCW Local Positioning - Ferizi, Alban; Kölpin, Alexander (Electrical and Electronic Engineering for Communication Workshop - Entwicklerforum - Fachmesse, 2012)
elib2cris::1512001600,ferizi2012a

Basis Forms of Switching Functions - Can, Yavuz; Fischer, Georg (10th International Conference on Electrical and Electronics Engineering (ELECO 2017), IEEE Turkey Section, 2017)
This paper presents extended forms, equations, and relations of switching function which are derived out of the theory of switching algebra and the combinational circuit design. Two extended forms and four already deﬁned standard forms of switching function, which are partly renamed, are presented. Out of the combinational circuit design these extended forms, the antivalence of disjunctions ADF and the equivalence of conjunctions ECF, are educed and thereby their algebraic expressions are set up. For that, conversion rules which enable the transformation of a disjunction of two variables in equivalence-operation of the same variables and the transformation of a conjunction consisting of two variables in antivalence-operation of the same variables will be lay down. Additionally, exclusion laws regarding to the extended forms ADF and ECF are set up which are deduce out of the distributive laws of the standard forms. Furthermore, in the case of orthogonal representation of these six function forms relations between them result. That means, by orthogonalization of a corresponding function form it can be easily transformed in an equivalent another function form.<br

BATS: Adaptive Ultra Low Power Sensor Network for Animal Tracking - Duda, Niklas; Nowak, Thorsten; Hartmann, Markus; Schadhauser, Michael; Cassens, Björn; Wägemann, Peter; Nabeel, Muhammad; Ripperger, Simon; Herbst, Sebastian; Meyer-Wegener, Klaus; Mayer, Frieder; Dressler, Falko; et al. (Sensors, 2018)
In this paper, the BATS project is presented which aims to track the behavior of bats via an ultra-low power wireless sensor network. An overview about the whole project and its parts like sensor node design, tracking grid and software infrastructure is given and the evaluation of the project is shown. The BATS project includes a lightweight sensor node that is attached to bats and combines multiple features. Communication among sensor nodes allows tracking of bat encounters. Flight trajectories of individual tagged bats can be recorded at high spatial and temporal resolution by a ground node grid. To increase the communication range the BATS project implemented a long-range telemetry system to still receive sensor data outside the standard ground node network. The whole system is designed with the common goal of ultra-low energy consumption while still maintaining optimal measurement results. To this end, the system is designed in a flexible way and is able to adapt its functionality according to the current situation. In this way it uses the energy available on the sensor node as efficient as possible. <br
Keywords: wireless sensor networks; animal tracking; adaptive sensor network

BATS: A system approach for animal tracking in resources limited wireless sensor networks - Kölpin, Alexander; Thielecke, Jörn (Workshop on Localization in Wireless Sensor Networks, 2017)
Keywords: BATS; Sensorknoten; Ortung

Battery Runtime Optimization Toolbox for Wearable Biomedical Sensors - Tobola, Andreas; Leutheuser, Heike; Schmitz, Björn; Hofmann, Christian; Struck, Matthias; Weigand, Christian; Eskofier, Björn; Fischer, Georg (13th International Conference on Wearable and Implantable Body Sensor Networks BSN, 2016)
Battery runtime is a critical concern for practical usage of wearable biomedical sensor systems. A long runtime requires an interdisciplinary low-power knowledge and appropriate design tools. We addressed this issue designing a toolbox in three parts: 1) Modular evaluation kit for development of wearable ultralow- power biomedical sensors; (2) Miniaturized, wearable, and code compatible sensor system with the same properties as the development kit; (3) Web-based battery runtime calculator for our sensor systems. The purpose of the development kit is optimization of the power consumption. Once optimization is finished, the same embedded software can be transferred to the miniaturized body worn sensor. The web-based application supports development quantifying the effects of use case and design decisions on battery runtime. A sensor developer can select sensor modules, configure sensor parameters, enter use case specific requirements, and select a battery to predict the battery runtime for a specific application. Our concept adds value to development of ultra-low-power biomedical wearable sensors. The concept is effective for professional work and educational purposes.
elib2cris::1512001600,tobola2016
Keywords: Batteries; Electrocardiography; Runtime; Power demand; Computational modeling; Temperature sensors; Biological system modeling

BayesRadar : Bayesian Metric-Kalman Filter Learning for Improved and Reliable Radar Target Classification - Dubey, Anand; Santra, Avik; Fuchs, Jonas; Lübke, Maximilian; Weigel, Robert; Lurz, Fabian (2021 IEEE 31st International Workshop on Machine Learning for Signal Processing (MLSP), 2021)
Automotive radar sensors offer a promising and effective modality for perception and assessment of the surrounding environment. A key element of environment sensing in automotive radars is the reliable detection, classification and tracking of vulnerable road users such as pedestrians and cyclists. In this paper, we propose an integrated Bayesian framework dubbed BayesRadar, which improves the overall classification accuracy by tracking the embedding vector of a neural network and its prediction uncertainty via recursive Kalman filtering over time. Apart from the classification accuracy of a model, a critical measure includes the analysis of statistical confidence over the target class score. Such measures for predicting the true correctness likelihood of the classification estimates are essential in safety-critical automotive applications. Therefore, in this paper, we present and evaluate the classification, embedding cluster score and statistical confidence performance of the proposed framework in the context of classifying vulnerable road users compared to state-of-art deep learning approaches. Furthermore, we demonstrate superior performance of the BayesRadar for unseen classes compared to long short-term memory based temporal tracking of the embedding vectors.<br
Keywords: Automotive radar; Bayesian framework; uncertainty estimation; vulnerable road user classification

Beamsteering for the Uplink of UMTS using Transmit Power Control Bits to iteratively determine the Antenna Weights - Schröter, Simon; Weigel, Robert; Fischer, Georg (IEEE International Conference on Wireless Information Technology and Systems (ICWITS), 2012, 2012)
elib2cris::1512001600,schroeter2012a

Bedarfsorientierte Beleuchtung für Mensch und Tier in der Milchviehhaltung - Werner, Daniel; Bernhart, Kristin; Eßelmann, Christian; Reiter, Klaus; Schwenzfeier-Hellkamp, Eva (23. Europäische Lichtkongress, LICHT2018, 2018)

Bedarfsorientierte LED-Beleuchtung in der Milchviehhaltung – Erarbeitung einer neuen Bewertungsgrundlage - Werner, Daniel; Müller, Maike; Reiter, Klaus; Schwenzfeier-Hellkamp, Eva (13. Tagung Bau, Technik und Umwelt in der landwirtschaftlichen Nutztierhaltung, 2017)

Behavioral Mixer Model for Rapid System Simulation of a 77GHz FMCW-Radar Transceiver - Günther, Oliver; Hartmann, Marcus; Wenig, Peter; Weigel, Robert (Asia-Pacific Microwave Conference, 2007. APMC 2007, 2007)
An advanced behavioral model of a 77 GHz SiGe Gilbert-type double balanced mixer is proposed, which is able to accurately model conversion gain compression and noise figure compression due to LO-power drop. The model is for use in system simulation of direct conversion automotive FMCW-radar transceivers. Model parameters can be easily extracted from 77 GHz measurement data. The model has been validated with measurement data and circuit level simulations and can be implemented in commercial simulators.
elib2cris::1512001600,guenther2007

Behavioral modelling of ICs for investigations of conducted emissions in automotive systems - Seibert, Günter; Metzner, D.; Klotz, F.; Pelz, Gerhard; Weigel, Robert (17th International Zurich Symposium on Electromagnetic Compatibility, 2006, 2006)
Because of increasing the electronics in a car, the automotive industry researches for simulating the whole system and how each element could influence another unexpected element. These are often caused by conducted emissions, which are a major challenge in the simulation of automotive systems. One important task is modeling power-ICs to simulate the switching depending on the load. Although circuit based models could perform this task in principle, the required computing-resources for simulation exceed acceptable limits. The applicability of a highly abstracted model will be shown and correlated with measurements and circuit based simulation. This work is a part to find a way to develop a load-independent model for EMC-simulation, but also doesn't need to much simulation-time. This work has been funded by the "Bayerische Forschungsstiftung" project MISEA
elib2cris::1512001600,seibert2006
Keywords: automotive electronics; electromagnetic compatibility; power integrated circuits; EMC-simulation; IC modelling; automotive systems; circuit based simulation; conducted emissions

Behavior of the LSAW loss in multi‐layer systems - Wallner, Paul; Ruile, Werner; Weigel, Robert (137th Meeting of the Acoustical Society of America (ASA), 1999)
Compared with common SAW, the leaky SAW shows attenuation even if material‐dependent loss types like viscosity, dielectric damping, or airloading are neglected. In fact, this typically LSAW loss is caused by a pure bulk wave emission into the piezoelectric substrate. For the search of low‐loss crystal cuts it is important that this kind of loss strongly depends on the crystal cut. Only such crystal cuts are important for technical use where this leaky loss shows a minimum. Moreover, former investigations confirmed that an additional metal layer on the piezoelectric substrate can shift the minimum loss to other crystal cut angles, e.g., the shift from 36rotYX to 42rotYX LiTaO3 with 10% Al. New computations show that this behavior can be understood as a general effect: The shift depends on the material constants of layer and substrate. In multi‐layer structures all the material constants influence the angle of minimum propagation loss. A distinct angle of minimum can be reached by using a distinct ratio of the layers. This means, if the ratio differs from 10% Al or the aluminum layer is covered with a second layer, the minimum of propagation loss due to bulk wave emission is shifted away from 42rotYX LiTaO3
elib2cris::1512001600,wallner1999

Beiträge zur Optimierung implantierbarer Sensorplattformen - Walk, Jasmin (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2015)

Beleuchtung im Milchviehstall - Technische Aspekte einer Stallbeleuchtung - Werner, Daniel; Schwenzfeier-Hellkamp, Eva (Baulehrschau-Sondertag, 2013)

Beleuchtung im Milchviehstall - Technische Aspekte einer Stallbeleuchtung - Werner, Daniel; Schwenzfeier-Hellkamp, Eva (Seminar der Landberatung Northeim-Uslar e.V., 2014)

Beleuchtung in der Stallumgebung - Lichtwahrnehmung von Mensch und Tier - Einsatz von klassischen Lichtquellen und Retrofit-Produkten - Werner, Daniel; Schwenzfeier-Hellkamp, Eva (Baulehrschau-Sondertag, 2015)

Beleuchtung und Beleuchtungstechnik im Rinderstall - Werner, Daniel; Schneider, Michael; Schwenzfeier-Hellkamp, Eva; Müller, Maike; Reiter, Klaus; Pelzer, Andreas (2016)

Bias-switched Down-Conversion Mixer for Flicker Noise Reduction in 28-nm CMOS - Ciocoveanu, Radu; Weigel, Robert; Hagelauer, Amelie Marietta; Issakov, Vadim (Texas Symposium on Wireless and Microwave Circuits and Systems, 2018)
This paper presents a modified Gilbert-cell mixer employing a novel biasing-scheme used to reduce the high Noise Figure, due to inherently high 1/f noise of MOS transistors. Switching the transistor from strong inversion to accumulation interferes with the self-correlation of the physical noisy process, which leads to a reduction in flicker noise. To illustrate this improvement, a comparison with a conventionally biased mixer is carried. Post-layout simulation results show that this mixer achieves a voltage conversion gain of 2.2 dB, a 1 dB compression point of 3 dBm and a 5 dB reduction in noise figure at 50 kHz, while it draws a current of 13 mA from a single 0.9 V supply. The occupied chip area is 0.5x0.94 mm². According to author’s knowledge this is the first time that bias switching technique is applied to a mixer at mm-wave frequencie

BiCMOS DeltaSigma Fractional-N Frequenzsynthesizer mit kurzer Einschwingzeit - Neurauter, Burkhard; Vuketich, R.; Märzinger, Günther; Weigel, Robert (Informationstagung Mikroelektronik, 2001)
elib2cris::1512001600,neurauter2001a
Keywords: BiCMOS; DeltaSigma Fractional-N Frequenzsynthesizer

Biological Optical-to-Chemical Signal Conversion Interface: A Small-scale Modulator for Molecular Communications - Grebenstein, Laura; Kirchner, Jens; Stavracakis Peixoto, Renata; Zimmermann, Wiebke; Wicke, Wayan; Ahmadzadeh, Arman; Jamali, Vahid; Fischer, Georg; Weigel, Robert; Burkovski, Andreas; Schober, Robert (ACM NANOCOM 2018: 5TH ACM INTERNATIONAL CONFERENCE ON NANOSCALE COMPUTING AND COMMUNICATION, 2018)
CRIS-Team WoS Importer:2019-02-22

Biological Optical-to-Chemical Signal Conversion Interface: A Small-scale Modulator for Molecular Communications - Grebenstein, Laura; Kirchner, Jens; Stavracakis Peixoto, Renata; Zimmermann, Wiebke; Irnstorfer, Florian; Wicke, Wayan; Ahmadzadeh, Arman; Jamali Kooshkghazi, Vahid; Fischer, Georg; Weigel, Robert; Burkovski, Andreas; Schober, Robert (IEEE Transactions on Nanobioscience, 2018)
Although many exciting applications of molecular communication (MC) systems are envisioned to be at microscale, the MC testbeds reported in the literature so far are mostly at macroscale. This may partially be due to the fact that controlling an MC system at microscale is challenging. To link the macroworld to the microworld, we propose and demonstrate a biological signal conversion interface that can also be seen as a microscale modulator. In particular, the proposed interface transduces an optical signal, which is controlled using a light-emitting diode (LED), into a chemical signal by changing the pH of the environment. The modulator is realized using Escherichia coli bacteria as microscale entity expressing the light-driven proton pump gloeorhodopsin from Gloeobacter violaceus. Upon inducing external light stimuli, these bacteria locally change their surrounding pH level by exporting protons into the environment. To verify the effectiveness of the proposed optical-to-chemical signal converter, we analyze the pH signal measured by a pH sensor, which serves as receiver. We develop an analytical parametric model for the induced chemical signal as a function of the applied optical signal. Using this model, we derive a training-based channel estimator which estimates the parameters of the proposed model to fit the measurement data based on a least square error approach. We further derive the optimal maximum likelihood detector and a suboptimal low-complexity detector to recover the transmitted data from the measured received signal. It is shown that the proposed parametric model is in good agreement with the measurement data. Moreover, for an example scenario, we show that the proposed setup is able to successfully convert an optical signal representing a sequence of binary symbols into a chemical signal with a bit rate of 1 bit/min and recover the transmitted data from the chemical signal using the proposed estimation and detection schemes. The proposed modulator may form the basis for future MC testbeds and applications at microscale.
Keywords: Microorganisms; Protons; Biomedical optical Imaging; Optical pumping; Optical Receivers; Optical sensors; Chemicals

Biowireless 2014 (feature column) - Kissinger, Dietmar (IEEE Microwave Magazine, 2013)
elib2cris::1512001600,kissinger2013a

BIST (Built-In Self-Test) Strategy for Mixed-Signal Integrated Circuits - Li, Hongzhi (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2004)

Block model of Microcontroller for Electromagnetic Immunity Simulation - Su, Tao; Unger, Markus; Steinecke, Thomas; Weigel, Robert (EMC Europe 8th International Symposium on Electromagnetic Compatibility, 2008)
elib2cris::1512001600,su2008d

Boolean Orthogonalizing Combination Methods - Can, Yavuz; Fischer, Georg (Fifth International Conference on Computational Science, Engineering and Information Technology, 2015)
In this paper a new logical operation method called “orthogonalizing difference-building” is presented. It is used to calculate the difference, but also the complement of a function as well as the EXOR and EXNOR of two minterms respectively two ternary-vectors or two functions respectively two ternary-vector-lists is presented. On the basis of this new method a further logical operation method called “orthogonal OR-ing” is going to be introduced. The advantages of both methods are their results, which are already available in an orthogonal form that has an essential advantage for continuing calculations. Since it applies, an orthogonal disjunctive normal form is equal to orthogonal antivalence normal form, subsequent Boolean differential calculus will be simplified.
elib2cris::1512001600,can2015
Keywords: Difference-Building; Orthogonality; TVL; Data Memory Request; Computing Time

Breitbandige Netzwerkanalyse auf Basis einer Sechstor-Topologie im Frequenzbereich zwischen 3 GHz und 30 GHz - Hofmann, Maximilian (RadCom, 2013)
Mit Hilfe einer Sechstor-Topologie lassen sich die Beträge und Phasenlagen zweier einfallender Wellen vergleichen und quantifizieren. Dies impliziert die Eignung einer Sechstor-Topologie zur vektoriellen Netzwerk-Analyse. Durch den Einsatz von breitbandigen Kopplern und Leistungsteilern (f_max/f_min > 9) lässt sich diese Architektur verwenden um eine Zweitor-Netzwerkanalyse im Frequenzbereich von 3 bis 30 GHz durchzuführen. Schaltungsentwurf, Feldsimulation und Messung wird im Rahmen des Vortrags vorgestellt.
elib2cris::1512001600,hofmann2013

Bridging the Gap: Extending MPEG Audio down to 8 kbit/s - Dietz, Markus; Herre, Jürgen; Teichmann, B; Brandenburg, Karlheinz (102nd AES Convention, 1997)
Vorträge und Veröffentlichungen auf Konferenzen_Gehörangepasste Datenreduktion

Bringing Portability to a New Level: A High-Sensitivity, Low-Power Monostatic CW Radar at 24 GHz - Peters, Sebastian; Horlbeck, Marie; Probst, Florian; Weigel, Robert (IEEE Microwave Magazine, 2022)
Radar technology offers unique advantages that distinguish it from conventional sensing technologies. Now, research on industrial sensor systems is rapidly increasing. Due to the massive integration of RF circuits in monolithic microwave integrated circuits in recent years, radar systems can be designed to be very compact, inexpensive, and at the same time, feature a low power consumption [1] , [2] . This development is also pushed by the digital transformation of production in various industries, commonly known as the fourth industrial revolution [3] , [4] . In industrial environments, radar technology offers various advantages over conventional sensors. The combination of high resolution, low power consumption, and operation in harsh environments makes radar sensors extremely attractive. Additionally, radar technology also stands out from other sensor technologies in the medical field. Radar systems can be used for simple presence monitoring or, due to the very high resolution, for gesture recognition or even for recording vital parameters. Minimal movements on the surface of the chest caused by respiration or heartbeat are strong enough to be detected by radar systems without contact [5] , [6] .<br

Broadband Characterization of Launchers and Transitions - Talai, Armin (2016)
Characterizing material properties with a high degree of precision requires very accurate sensors, which means that the properties of the sensor itself must also be accurately characterized. Simulation allows the properties of elements of the test equipment to be calculated in isolation or be integrated into the simulation model for the test set-up, and allows the design of the sensor to be optimized. This article will demonstrate how CST® STUDIO SUITE® was used to simulate and optimize a coaxial-microstrip transition for a material characterization measurement system, including the effect of the probes themselves, and analyze the effect of surface roughness on the properties of the sensor.
elib2cris::1512001600,talai2016b
Keywords: Launchers; Transitions; Material Characterization; Surface Roughness

Broadband Circuit Techniques for Multi-Terahertz Gain-Bandwidth-Product Low-Power Applications - Radwan, Ahmed; Weigel, Robert; Kissinger, Dietmar (IEEE Transactions on Microwave Theory and Techniques, 2015)
In this paper, two proposed bandwidth (BW) extension techniques are discussed and analytically analyzed. The capabilities of the proposed feedback techniques are demonstrated with two design examples of different circuitry, supported by simulation and measurement results. The first design example is a broadband low-power active balun, employing one of the presented feedback techniques. It is capable of operating with a gain of 2.2 dB and BW of more than 70 GHz. The amplitude imbalance is less than 2.4 dB, while the phase imbalance is below 7 ° up to 60 GHz and 14 ° up to 70 GHz, consuming a low-power of 29.7 mW. The second design example is a differential three-stage amplifier, incorporating the two techniques, where their combined performance achieves a gain of 54 dB and a 3-dB BW of 25 GHz, resulting in a gain-BW product (GBP) of 12.5 THz, with a power consumption of 180 mW from a 3.3-V supply. The chips are fabricated in a 0.35- μm SiGe:C bipolar technology with a ft/ fmax of 200/250 GHz.
elib2cris::1512001600,gharib2015

Broadband high-efficiency monolithic InGaP/GaAs HBT power amplifiers for 3G handset applications - Jäger, Herbert; Grebennikov, Andrej; Heany, E.; Weigel, Robert (IEEE International Mircowave Symposium Digest, 2002)
In this paper, an approach to high efficiency power amplifier performance over a wide frequency range is discussed. Results for practical implementation of a multiband and multi-mode handset power amplifier are shown. Measurements demonstrate feasibility of the concept for WCDMA, DCS1800 and PCS1900 high-efficient operation. A PAE of better than 38% at 27 dBm output power and an ACLR of -37 dBc in WCDMA operation, as well as greater than 50% PAE at 30 dBm output power in the DCS1800 and PCS1900 band are documented
elib2cris::1512001600,jaeger2002

Broadband Low-Loss Fan-In Chip-to-Package Interconnect Enabling System-in-Package Applications Beyond 220 GHz - Pfahler, Tim; Breun, Sascha; Engel, Lukas; Geissler, Christian; Schür, Jan; Vossiek, Martin (IEEE Transactions on Components, Packaging and Manufacturing Technology, 2024)
This paper presents a broadband low-loss fan-in wafer level ball grid array (WLB) vertical through-mold-via (TMV) interconnect that enables highly integrated system-in-package (SiP) applications beyond 220 GHz. The dedicate advantage of the proposed approach is to further minimize the separation between package components (e.g., antenna in package (AiP)) and on-chip receiver or transmitter chain. To demonstrate the robustness of the TMV interconnect design, the necessity for co-simulation of the integrated circuit (IC) package and the IC itself during the package-design is shown. Therefore, an in-depth analysis of the suppression of parasitic mode oscillation inside silicon is carried out. Furthermore, the parasitic radiation loss at the TMV interconnect discontinuity is given and a verification of the proposed TMV due to high agreement of simulation and measurement results is demonstrated. The interconnect has been verified with a measured 10 dB return loss bandwidth of 38 GHz and a de-embedded insertion loss of less than 2.8 dB at 275 GHz, which enables a compact low-loss broadband signal transition from active IC components in the backend-of-line (BEOL) to passive components in package. Compared to fan-out WLB, the developed fan-in WLB solution enables higher integration density of active and passive components with the shortest interconnects for minimal insertion loss. Thus, the proposed fan-in TMV packaging provides a very compact, easy-to-assemble and cost-efficient alternative for SiP designs for future broadband communication and sensing solutions.<br
CRIS-Team Scopus Importer:2024-04-19
Keywords: Packaging; Antennas; Assembly; Integrated circuit interconnections; Copper; Broadband communication; Bandwidth; Assembly; fan-in WLB (wafer level ball grid array); fan-out WLB; heterogeneous system design; interconnect; signal transition characterization; system-in-package (SiP); wafer level packaging

Broadband Low Power Transmitter Based in SiGe Technology on Maximum Length Sequences - Radwan, Ahmed (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2016)

Broadband Millimeter-Wave Receiver Front-Ends in Silicon-Germanium Technology for Multi-Band Communication Systems - Nasr, Ismail; Weigel, Robert; Kissinger, Dietmar (IEEE International Microwave Symposium, 2013)
Millimeter-wave frequency-agile front-ends capable of operating at different frequency bands offer an attractive solution for multiband communications. In this paper we present a fully integrated wide-band quadrature receiver covering the two point to point communication bands from 71 to 76 GHz and 81 to 86 GHz and the automotive radar band at 77 GHz. The receiver was fabricated using a low-cost SiGe technology with an ft/fmax of 200/250 GHz. The chip contains a wide-band LNA, Wilkinson power divider, down conversion mixers, two stage polyphase network, VCO, and frequency prescaler. The VCO achieves an ultra high tuning range of 33% between 64 and 89 GHz. Each receiver path (I/Q) has a measured conversion gain between 17 to 23 dB over the operating frequency range. The receiver has a minimum NF of 8 dB, and an input referred compression point of -22 dBm. The complete chip consumes 220mA of current from a 3.3V supply. Index Terms—
elib2cris::1512001600,nasr2013

Broadband Multi-Octave Receiver from 1-32 GHz for Monolithic Integrated Vector Network Analyzers (VNA) in SiGe-Technology - Dietz, Marco; Girg, Thomas; Bauch, Andreas; Aufinger, Klaus; Hagelauer, Amelie Marietta; Kissinger, Dietmar; Weigel, Robert (European Microwave Integrated Circuits Conference, 2017)

Broadband SAW phase-weighted chirp transducers for integrated acoustooptic scanners - Weigel, Robert; Anemogiannis, Kimon; Russer, Peter (Proc. Ultrasonics International, 1993)
elib2cris::1512001600,weigel1993k

Broadcast and Multicast In The Sector Of Several Verticals - An Evaluation Of The Current Status - Hertlein, Markus; Kundikov, Andriy; Fischer, Georg (2017 3rd IEEE International Conference on Computer and Communications (ICCC), 2018)
In times of rare spectrum our generation has to think if it is useful that every service has its own spectrum. PMSE, broadcast and BOS services use different frequencies an methods to solve the current situation. Because of the upcoming 5G standard the question arises if mobile communication can support the other services or even in the end if there can be one platform for all services and can use all frequency bands with the newest technologies. In this paper we consider this question in the case of broadcasting and PMSE services. There are two excellent projects in which we simulate, measure and analyse the chances for 5G as a platform for all services. The focus lies on the Unicast and Multicast, as well as SISO and SIMO transmission modes. A simulator, which is implemented in Matlab, is used as the simulation tool. The simulation results are presented in dependence of the bit error rate over the signal to noise ratio. This allows a qualitative statement about the reception qualit
Keywords: Broadcast; Mulitcast; LTE

Broadcast precoding for massive MIMO subject to an instantaneous total power constraint - Sedaghat, Mohammad A.; Müller, Ralf; Fischer, Georg (2014 IEEE Global Communications Conference, GLOBECOM 2014, 2014)
We design a new precoding scheme for massive multiple-input multiple-output (MIMO) systems subject to an instantaneous total power constraint. Unlike the classical way of designing precoders, we use a more realistic model for power amplifiers by considering their maximum power. The considered power constraint is applicable in the single-RF MIMO transmitter which has been proposed recently for massive MIMO systems. For sake of analysis, i.i.d. Gaussian signals are considered. It is shown that the designed precoding scheme results in a good performance in terms of signal to interference plus noise ratio (SINR) at the receivers and power efficiency at the transmitter. It is shown that the power efficiency utilizing this precoding scheme is almost equal to the case of constant envelope signals. Since the proposed precoding limits the total transmit power, there is no need for peak-to-average power ratio (PAPR) reduction algorithms.
Keywords: crest factor; massive MIMO; matching networks; Multiple antennas; multiple-input multiple-output (MIMO) systems; peak-to-average power ratio (PAPR)

Building Blocks of Cooperative Relaying in Wireless Networks - Elmenreich, Wilfried; Marchenko, Nikolaj; Adam, Helmut; Hofbauer, Christian; Brandner, Günther; Bettstetter, Christian; Huemer, Mario (Elektrotechnik und Informationstechnik, 2008)
elib2cris::1512001600,elmenreich2008

Built-in Self-Test für RFICs - Münker, Christian; Weigel, Robert (EEEfCOM, 2006)
elib2cris::1512001600,muenker2006

Bursting: Increasing Energy Efficiency of Erasure-Coded Data in Animal-Borne Sensor Networks - Cassens, Björn; Hartmann, Markus; Nowak, Thorsten; Duda, Niklas; Thielecke, Jörn; Kölpin, Alexander; Kapitza, Rüdiger (ESWN 2019, 2019)
Observing the (social) behavior of animals and especially bats contributes to improved epidemic forecasts and improved protection of rare or endangered species. For this task, animal-borne sensor nodes are powerful tools since they allow collecting more information at less influence to the species compared to traditional radio telemetry. However, as bats are inherently small vertebrates, a strict weight limit of 2 g is dictated for attached sensor nodes. To acquire enough data, the sensor nodes must achieve a runtime of at least two weeks, which demands a rigorous energy management. As the data transmission is the most energy hungry task, minimizing the energy demand in this segment is a key to achieve the desired runtimes. In this paper we present a novel technique that enables bursts of erasure coded data without sacrificing reliability (in a wildlife setting). To keep data losses at a minimum, our approach exploits the characteristics of the erasure channel and combines encoded packets in smart way. We evaluated this approach extensively with experiments, field tests and a theoretical analysis. The results show a decreased energy demand by 30.177 % to 36.951 % while the data rate is increased up to a factor of 4 at the same tim

Busbar Current Measurement with Elliptical Sensor Arrays without Conductor Specific Calibration - Weiss, Roland; Zapf, Florian; Skelly, Anna; Weigel, Robert (IEEE Transactions on Instrumentation and Measurement, 2021)
In highly efficient power electronic systems, circular arrays of magnetic field sensors offer numerous advantages compared to older magnetic core-based sensors. They feature low power consumption, low weight and a high immunity to external magnetic fields. In power converters, conductors with a rectangular cross section, a small height, and a large width are widely used. Thus, an elliptical sensor array could reduce the space needed for the current sensor e.g. in a power converter by a factor of four or more compared to a circular sensor array. In this work, we theoretically and experimentally study the sensitivity error caused by the change of the conductor geometry. Therefore, we calibrated different elliptical sensor arrays on a circular conductor and determined the sensitivity error for the use of flat conductors with different widths. This calibration on a circular conductor avoids a costly conductor specific calibration of the sensor array in the application. Two different distribution methods for elliptical sensor arrays and different ratios of the semi-axes are considered. In addition, the influence of the number of sensors and the starting position for the sensors are examined. The presented elliptical sensor arrays can be used to measure the current carried by a flat conductor largely independent of its width. For some aspect ratios, they even offer a lower sensitivity error than circular sensor arrays. In the conclusion section, design considerations for those elliptic sensor arrays are given.
CRIS-Team Scopus Importer:2021-05-21
Keywords: Ampè re’ s law; bus bar; Calibration; circular sensor array; Conductors; contactless current measurement; Current measurement; elliptical sensor array; flat conductor; Hall effect sensors; Magnetic circuits; Magnetic cores; magnetic field sensors; Sensitivity; Sensor arrays

Bus configuration and bus load in a tractor fertilizer spreader system (LBS by DIN 9684) - Auernhammer, Hermann; Ostermeier, Ralf; Demmel, Markus; Weigel, Robert (Agricultural Engineering (AGENG), 1996)
elib2cris::1512001600,auernhammer1996

C2 and Payload in one Link – Chances and Challenges of OFDM - Blümm, Christian; Heller, Christoph (Convention for Telemetry, Test Instrumentation and Telecontrol, 2012)
Unmanned aerial vehicles (UAVs), as well as unmanned ground vehicles (UGVs), are increasingly used in military operations to avoid endangerment of pilots and soldiers. Also civil use cases for such kind of platforms are emerging, for instance for surveillance or search and rescue missions. The operation of unmanned vehicles in most cases requires two different types of data connections: A command and control (C2) link to pilot the unmanned vehicle in its mission environment as well as a payload link to transfer sensor or video data to the ground control station. While the C2 link has to be optimized with respect to maximum robustness, the sensor data link has to provide data rates in the range of several Mbit/s for reasonable operation. The conventional solution is to use two independent data links, each with a modulation that is optimized for its transmission requirements. The usage of Orthogonal Frequency Division Multiplexing (OFDM) allows the realization of multiple logical links with different transmission characteristics in a single waveform and in a single modem. The set of orthogonal carrier functions provided by an OFDM modulation for this purpose is partitioned into multiple sets of carriers that are assigned to the individual logical links. The different carrier sets are used with specific subcarrier modulation schemes and code rates, depending on the robustness required by the logical link. These parameters, together with the number of subcarriers per carrier set, determine the usable data rate of each logical link. In this paper, we present the design of an OFDM waveform for the simultaneous transmission of control and payload data in a UAV/UGV scenario for security services video surveillance, originating from the German funded project “Sichere Navigation für autonome Robotik-Plattformen” (SiNafaR). We point out specific design considerations as well as benefits and drawbacks of this integrated data link solution, and we give performance figures of the final link implementation to validate the concep
elib2cris::1512001600,bluemm2012

Calibration scheme for microwave biosensors using exclusively liquid calibration standards - Michler, Fabian; Lenze, Felix; Schüßler, Martin; Maune, Holger; Jakoby, Rolf (IEEE Topical Conference on Biomedical Wireless Technologies, Networks, and Sensing Systems (BioWireleSS), 2016)

Cancellation of even-order intermodulation distortion in communication RFICs - Dufrene, Krzysztof (GMM Workshop "Mikroelektronik Anwendungen", 2006)
elib2cris::1512001600,dufrene2006b

Cancellation of Interference from Synchronization and Pilot Channels on High Speed Downlink Shared Channel in UMTS - Freudenthaler, Klaus; Kaltenberger, F.; Paul, Stefan; Mecklenbraeuker, Christoph; Huemer, Mario; Springer, Andreas (11th European Wireless Conference, 2005)
In this contribution, we describe a newly developed simulation environment for High Speed Downlink Packet Access (HSDPA) in UMTS Release 5 and beyond. The simulation environment implements the downlink physical layer for the High Speed Downlink Shared Channel (HS-DSCH) in detail, whereas the associated signalling messages are idealized as error free. The interference from signalling and data channels on the HS-DSCH is modelled adequately. As a general guideline for system settings in the simulations, we use the test cases specified in 3G TS 25.101 whenever applicable. It is shown that the interference generated by the Synchronization Channel (SCH) and Common Pilot Channel (CPICH) has considerable impact on the error statistics of the HS-DSCH. Therefore, it is worthwhile to implement interference cancellation for the SCH and CPICH in future mobile receivers for HSDPA.
elib2cris::1512001600,freudenthaler2005
Keywords: UMTS; Interference

Capacitive Sensing for Magnetic Nanoparticles in Molecular Communication - Bartunik, Max; Reichstein, Johannes; Kirchner, Jens (2022 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2022)
Keywords: Molecular Communication; Magnetic Nanoparticles; Capacitive Sensor

Cardiopulmonary-Resuscitation Feedback Simulation - Hofmann, Maximilian (CST European User Conference, 2012)
A cardiopulmonary resuscitation feedback system must measure the compression depth and rate to ensure a sufficient cardiac massage. This contribution presents a novel approach to CPR measurement systems. The introduced concept evaluates the compression depth and rate with two antennas which are coupled through the thorax. For this reason, different 3D thorax models (deformable) were investigated and simulated with four different antenna pairs. The antennas are centered between 868 MHz and 2.4 GHz and matched to the upper skin layer impedance. The simulation results are evaluated in animal and human experiments finally.
elib2cris::1512001600,hofmann2012d

Case Study on Energy Efficient Communication Design - Starzer, Florian; Papanikolaou, Antonis; Miranda, Miguel; Catthoor, Francky; Huemer, Mario (Embedded and Mobile Systems Workshop, 2005)
elib2cris::1512001600,starzer2005
Keywords: Energy Efficiency; Communications

Case Study on Memristor-Based Multilevel Memories - Söll, Christopher; Reichenbach, Marc; Röber, Jürgen; Hagelauer, Amelie Marietta; Weigel, Robert; Fey, Dietmar (International Journal of Circuit Theory and Applications, 2018)
In this work, the benefits of memristor-based multilevel memories are described along with their design problems. Starting with measurements of discrete actual devices, a discrete memristor based multilevel memory is developed. It uses a printed circuit board in order to connect eight packaged memristors from Bio Inspired to test a ternary Arithmetic Logic Unit (ALU) on a field programmable gate array (FPGA). These circuits are then integrated in the second proposed memory system based on a 150nm CMOS process that can be equipped with memristors on top of the metal layers. This integrated solution includes proper read-out, erase and write circuits to control real memristors, and 32x32 memristive memory cells. It is compared to a common static random-access memory (SRAM) in terms of area, computation speed and power consumption showing benefits for memory sizes bigger than 70 words. Since yield and device variations are still a big issue in memristor fabrication, methods to counter these problems are also proposed in the end. An actual implementation should offer several trimming solutions to ensure proper functionality of a prototype memory as well as a power-on calibration, until these problems are solved. The development of the presented memories is not only based on different models but also measurements done with real devices.
elib2cris::1512001600,soell2017
Keywords: Memristor; Multi-Level Memory; Memory Interface; Memristive Computing; GRK-1773

CDMA in the context of OFDM and SC/FDE - A Comparision Study - Witschnig, Harald; Huemer, Mario; Springer, Andreas; Stuhlberger, Rainer (Proc. 5th International Workshop on Multi-Carrier Spread Spectrum, 2005)
Topic of this work is to characterize the frequency domain equalization concepts of OFDM (Orthogonal Frequency Division Multiplexing) and SC/FDE (Single Carrier Transmission with Frequency Domain Equalization) in the context of CDMA (Code Division Multiple Access) - as besides efficient equalization in the frequency domain, future communication system will also be judged by their possibilities to be combined with multiple access techniques. Due to specific characteristics of the invvestigated system, also their behaviour in the context of CDMA is a differen one and advantages and disadvantages of the underlying concepts will be pointes out. Aspects as preferred spreading codes, despreading in the frequency domain, possible performance in the context of multi path propagation, or multi user detection are investigated.
elib2cris::1512001600,witschnig2005a

CEPT FGRXIM(19)002 Algorithm Requirements - Fischer, Georg; Cwik, Andrzej; Beaufort, Daniel (2019)
Keywords: RX Intermodulation; IP3

CEPT FM51(19)93, Advanced Receiver Design for Cancelation of DME Interference into PMSE - Irnstorfer, Florian; Fischer, Georg (ECC CEPT FM51, 2019)

CEPT SE7(17)044 Intermodulation between LTE and NB systems in the 400 MHz band - Fischer, Georg; Cwik, Andrzej (2017)
Keywords: RX Intermodulation; Smart Grid; LTE M2M

CEPT SE7(18)018 SEAMCAT Plug-in for IM Studies - Fischer, Georg; Cwik, Andrzej (2018)
Keywords: RX Intermodulation

CEPT SE7(18)052 Methodology for_assessing compatibility WB vs NB systems - Fischer, Georg; Cwik, Andrzej (2018)
Keywords: Non-linear Circuits; RX Intermodulation

CEPT SE7(18)054 Dependence of IM products on tone spacing and occupied bandwidth - Fischer, Georg; Cwik, Andrzej (2018)

CEPT SE7(18)058 Reaction on proposed SEAMCAT IM plugin - Fischer, Georg; Cwik, Andrzej (2018)

CEPT SE7(18)071 Suggestion for Effective IIP3 and Effective Selectivity - Fischer, Georg; Cwik, Andrzej (2018)

CEPT SE7(18)072 Draft ECC Report on LTEin400 Annex 3 based on comments SE(18)041 - Fischer, Georg; Cwik, Andrzej (2018)
Keywords: RX Intermodulation

CEPT SE7(18)102 Reference Values for RX Intermodulation - Gäde, Bernhard; Fischer, Georg (2018)
Keywords: Receiver Intermodulation; RX non-linearity; IIP3

CEPT SE7(18)103 Status of Seamcat IM plugin validation - Fischer, Georg; Gäde, Bernhard (2018)
Keywords: RX Intermodulation

CEPT SE7(18)105 Efficient frequency domain algorithms for calculation of RX Intermodulation - Gäde, Bernhard; Fischer, Georg (2018)
Keywords: RX Intermodulation; non-linear Circuit Technology; non-linear systems

CEPT SE7(18)106 Impact of LTE BS Activity Factor on TETRA RX Intermodulation - Gäde, Bernhard; Fischer, Georg (2018)
Keywords: RX Intermodulation; BS activity factor

Challenges and opportunities toward a MEMS-based RF frontend for LTE - Silva Cortes, Victor Arturo (Electrical and Electronic Engineering for Communication Workshop - Entwicklerforum - Fachmesse, 2013)
elib2cris::1512001600,cortes2013

Challenges in Automotive Electromagnetic Compatibility Modeling and Simulation - Neumayer, Roland; Weigel, Robert (Electromagnetics in a Complex World - Challenges and Perspective, 2003)
Electromagnetic compatibility (EMC) issues are increasingly important to the automotive industry. Problems arise from the growing use of electronic systems on the one hand and the lack of flexibility in placement or design of electronic modules on the other hand. Consequently, an accurate system-level EMC analysis is required from early stages of the vehicle design process. This paper presents a concurrent EMC simulation process that incorporates the EMC behavior of the electronic equipment in the system-level automotive EMC simulation. The proposed process helps to identify and reject potential EMC problems introduced by new technologies. This cuts the risk of EMC failure and avoids costly and time-consuming redesigns.
elib2cris::1512001600,neumayer2003a

Challenges in Automotive Electromagnetic Compatibility Modeling and Simulation - Neumayer, Roland; Weigel, Robert (Electromagnetics in a Complex World - Challenges and Perspectives, 2004)
UnivIS-Import:2015-04-20:Pub.2004.tech.IE.LETE.challe

Challenges in Automotive Electromagnetics Compatibility Modeling and Simulation - Neumayer, Roland; Weigel, Robert (Springer, 2012)
Electromagnetic compatibility (EMC) issues are increasingly important to the automotive industry. Problems arise from the growing use of electronic systems on the one hand and the lack of flexibility in placement or design of electronic modules on the other hand. Consequently, an accurate system-level EMC analysis is required from early stages of the vehicle design process. This paper presents a concurrent EMC simulation process that incorporates the EMC behavior of the electronic equipment in the system-level automotive EMC simulation. The proposed process helps to identify and reject potential EMC problems introduced by new technologies. This cuts the risk of EMC failure and avoids costly and time-consuming redesigns.
elib2cris::1512001600,neumayer2012

Challenges in Miniaturized Automotive Long-Range Lidar System Design - Fersch, Thomas; Weigel, Robert; Kölpin, Alexander (SPIE Defense + Commercial Sensing, 2017)

Challenges in Radio Electronics - Weigel, Robert (EUROCON, 2007. The International Conference on "Computer as a Tool", 2007)
elib2cris::1512001600,weigel2007d
Keywords: mobile radio; plenary lecture; radio electronics; Acoustic waves; Acoustical engineering; CMOS technology; Consumer electronics; Integrated circuit technology

Challenges in RF-DPLL Design for Wideband Phase Modulation supporting SC-FDMA in LTE Uplink - Buckel, Tobias; Wicpalek, Christian; Mayer, Thomas; Tertinek, Stefan; Preyler, Peter; Neurauter, Burkhard; Weigel, Robert; Ußmüller, Thomas (44th European Microwave Conference, 2014)
elib2cris::1512001600,buckel2014

Challenges on COTS-based Radiation Tolerant Communication System Design - Müller, Steffen; Kölpin, Alexander (DLR Bauteilekonferenz, 2017)

Channel Characterization at 77 GHz for Vehicular Communication - Lübke, Maximilian; Hamoud, Hussein; Fuchs, Jonas; Dubey, Anand; Weigel, Robert; Lurz, Fabian (IEEE Vehicular Networking Conference, 2020)
In this paper, the investigation of the channel characteristics for mmWaves is addressed due to its recent sparked interest in modern communication technologies. Modern intelligent transportation systems require higher data rates and, therefore, more bandwidth, utilization of higher frequencies, which can provide these needs, get more and more in focus in the context of 5G. As part of our current research, the proposed work aims to give a deeper understanding of the channel characteristics and wave propagation at 77 GHz, especially for automotive use cases like platooning or intersection assistant. Typical traffic scenarios, starting with a rural street and proceeding with a highway scene, were reconstructed using the commercial simulator WinProp. Furthermore, the scenarios are evaluated by including additional obstacles, like vehicles and traffic signs. Time-varying environments with driving vehicles with either line-of-sight (LOS) as well as non-LOS (NLOS) connections were investigated. The results reveal significant changes in the channel impulse response for one time step, when, especially relevant in the NLOS case, a new reflection path gets available as scattering and reflection paths have more than 25 dB difference in receiving amplitude. Therefore, the antenna alignment and the environment had a strong influence. Thus, it could be shown that scatters like traffics signs cause power fading for the LOS connection, whereas they benefit the NLOS case, by enabling communication at all. In future research, the channel models will be further addressed and expanded to design a link that is capable of communicating safety-relevant information and hold the high demands on latenc

Channel equalization for OFDM communication on a runtime-flexible SDR platform - Blümm, Christian; Elefsiniotis, Alexandros; Heller, Christoph; Weigel, Robert (RADCOM, 2013)
Each communication system requires channel equalization to compensate systematic distortions resulting from propagation effects like multipath spread or Doppler shift. A major advantage of Orthogonal Frequency Division Multiplexing (OFDM) is the simplicity of channel equalization in frequency domain. The channel state information for adequate equalization can be gained by transmitting known signals, called pilot tones. The way of distributing those pilots among payload tones and the way of interpolating them is decisive for the equalization quality and must be matched to the channel characteristic. This study compares different pilot distributions and interpola- tion techniques and gives details of a runtime-flexible implementation on a self-desig- ned FPGA-based Software Defined Radio (SDR) platform.
elib2cris::1512001600,bluemm2013

Channel Measurements for the Evaluation of Evolving Next Generation Wireless Railway Communication Applications - Elkholy, Kariem; Lichtblau, Johann; Reißland, Torsten; Weigel, Robert; Kölpin, Alexander (German Microwave Conference (GeMiC), 2020)

Channel Parameter Studies of a Molecular Communication Testbed With Biocompatible Information Carriers: Methods and Data - Bartunik, Max; Teller, Janina; Fischer, Georg; Kirchner, Jens (IEEE Transactions on Molecular, Biological and Multi-Scale Communications, 2023)
Testbeds play an essential role in the development of real-life molecular communication applications and experimental validation of communication channel models. Although some testbed concepts have been published in recent years, very few setups are inherently suitable for biomedical applications. Furthermore, systematic experimental data of a wide parameter field for molecular communication is scarce and often difficult to generate. In this work, a biocompatible testbed for molecular communication with magnetic nanoparticles is used to investigate a series of transmission channel parameters. The observed results are discussed in the context of a laminar flow channel. All experimental data regarding the parameter studies as well as an additional data set for a large binary transmission sequence is provided as a supplement to this publication. The data is available on a public server to allow for further use by other researchers.
CRIS-Team Scopus Importer:2023-11-03
Keywords: Coils; Iron; methods; Micropumps; Molecular communication; molecular communication; nanoparticles; parametric data; Receivers; spions; Superparamagnetic iron oxide nanoparticles; testbed; Transmitters

Channel Parameter Studies of a Molecular Communication Testbed With Biocompatible Information Carriers: Methods and Data - Bartunik, Max; Teller, Janina; Fischer, Georg; Kirchner, Jens (IEEE Transactions on Molecular, Biological and Multi-Scale Communications, 2023)
Testbeds play an essential role in the development of real-life molecular communication applications and experi- mental validation of communication channel models. Although some testbed concepts have been published in recent years, very few setups are inherently suitable for biomedical applications. Furthermore, systematic experimental data of a wide parameter field for molecular communication is scarce and often difficult to generate. In this work, a biocompatible testbed for molecular communication with magnetic nanoparticles is used to investi- gate a series of transmission channel parameters. The observed results are discussed in the context of a laminar flow channel. All experimental data regarding the parameter studies as well as an additional data set for a large binary transmission sequence is provided as a supplement to this publication. The data is available on a public server to allow for further use by other researchers.
Keywords: Molecular communication; nanoparticles; spi- ons; parametric data; methods; testbed.

Channgel Impulse response Inside a Magnetic Resonance Imaging Device at 0.8 GHz to 27 GHz - Wiehl, Michael; Schwarzer, Stefan; Fischer, Georg; Weigel, Robert; Kölpin, Alexander (19th International Conference on Microwave Radar and Wireless Communications (MIKON), 2012, 2012)
Up to now, wireless transmission in a magnetic resonance imaging (MRI) device is not used extensively for sensor networks or data transmission. Wireless sensors measuring physiological parameters like pulse, ECG, blood pressure or temperature would increase patient safety during a measurement. Beside and rather more interesting is the transmission of MRI sensor data. Patients benefit from higher comfort in the magnet and faster preparation for a measurement procedure. The wireless channels in an MRI device are not well studied at present. In this paper we give a first overview of the available antenna configurations for wireless links and summarize published results. As an MRI device is located in a shielded chamber, the frequency range for a transmission can be chosen freely above the resonance frequencies of the nuclei. To get an insight in the MRI channels we studied in a first approach three exemplary channels at the GSM-900 band, the 5 GHz WLAN band and the 24 GHz ISM band in three scenarios: empty, a real patient, a NaCl-filled tube.
elib2cris::1512001600,wiehl2012a
Keywords: UHF antennas; biomedical MRI; biomedical communication; biomedical telemetry; microwave antennas; radio links; transient response; wireless channels

Characterization and Design of Small Array Antennas for Direction-Of-Arrival Estimation for Ultra-Wideband Industrial FMCW Radar Systems - Gardill, Markus (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2015)

Characterization and improvement of GaAs HEMT analog switches for sampled-data applications - Feng, Shen; Seitzer, Dieter (IEEE Journal of Solid-State Circuits, 1994)
This paper presents design consideration an experimental comparison of GaAs HEMT analog switches for high-speed and high-precision sampled-data applications. At first, basic pass-transistor switches fabricated in a 0.5-mum GaAs HEMT technology are measured for characterization of transient errors induced due to clock-feedthrough and charge transfer. In order to improve the switch dynamic performances, a dual dummy transistor compensation technique is used and related driver circuitry is developed. On-wafer measurements demonstrate that the improved switch provides a significant reduction of the transient errors, a reasonable dynamic range, and a high isolation. The switch with a 0.53 pF load capacitor achieves a total harmonic distortion below -55 dB and -38 dB at 10 MHz and 1.0 GHz clock frequency, respectively.
Keywords: INTEGRATED CIRCUITS; ANALOG SWITCHES; GALLIUM ARSENIDE

Characterization and Modeling of Continuously Tunable MEMS Varactor - Lourandakis, Errikos; Fischer, Georg; Weigel, Robert (German Microwave Conference, 2009, 2009)
In this work a circuit model for a continuously tunable varactor is presented which is based on a microelectromechanical system (MEMS). This behavioral model can be implemented in commercially available simulation tools and allows for complete circuit simulations in terms of small- and large-signal performance, as well as for transient and envelope responses. For the present implementation Agilent's ADS is used but the modeling methodology can be generalized for use in other tools as well. For the MEMS varactor which is investigated in this paper good agreement is obtained between simulated and measured data. The capacitance variation for different tuning voltages as well as the frequency and power dependency of the component are discussed. For a bias voltage range up to 130 V a capacitance tuning ratio of more than 5:1 is obtained. The excellent linearity provided by minimal self actuation effects qualify the component for use in high power applications.
elib2cris::1512001600,lourandakis2009b
Keywords: continuously tunable; mems; varactor; microelectromechanical

Characterization and Modeling of Nonlinearities in RF BAW Components for Mobile Communication - Hagelauer, Amelie Marietta; Akstaller, Wolfgang; Tag, Andreas; Weigel, Robert (Sixth International Symposium on Acoustic Wave Devices for Future Mobile Communication, 2015)
elib2cris::1512001600,hagelauer2015

Characterization and Production of PCB Structures With Increased Ratio of Electromagnetic Field in Air - Sepaintner, Felix; Scharl, Andreas; Röhrl, Franz Xaver; Bogner, Werner; Zorn, Stefan (IEEE Transactions on Microwave Theory and Techniques, 2020)
Producing passive printed circuit board (PCB) structures in the millimeter-wave range includes some fundamental challenges, such as low manufacturing costs and high fabrication accuracy. These aspects, in general, have to be combined with low signal attenuation, precise simulation models, and a reliable producibility. This article shows a new method to manufacture different kinds of passive RF waveguides with reduced attenuation and decreased electrical length on low-cost PCB substrates. First, the complex material parameters of the used substrate and the used copper foil are extracted from 10 to 100 GHz to have accurate simulation models in CST Microwave Studio. This is necessary because the parameters provided by the manufacturer are often no longer generally valid in this frequency range. In addition, PCB materials have a signiﬁcantly higher surface roughness compared with conventional materials for millimeter-wave applications. Therefore, the correct determination and the correct modeling of surface roughness is particularly important. Next, laminate is removed partially on the outer layer of the PCB to increase the electromagnetic ﬁeld ratio in air. The undesired substrate is removed by a CO2 laser drilling machine by setting narrow drills sequentially. The RF performance of these waveguides is compared with those manufactured in conventional PCB technology according to attenuation and producibility. <br
Keywords: Complex permittivity; complex surface impedance; gradient model; material characterization; passive microstrip ﬁlters; printed circuit board (PCB); reduced tolerances; sequential pre-etching (SPE); surface roughness; transmission lines; wet-chemical etching

Characterization and Simulation of Bi-Quadratic Coplanar Waveguide Tapers for Time-Domain Applications - Thomann, Wolfgang; Isele, Bertram; Stöckeler, F.; Weigel, Robert; Russer, Peter (IEEE MTT-S International Microwave Symposium Digest, 1993, 1993)
The design and performance of a novel coplanar waveguide (CPW) taper for picosecond pulse applications is described. Tapers with widely differing widths varying from 62.5 mu m to 900 mu m are investigated. The circuit characteristics were simulated in both time domain and frequency domain using a 3-D transmission-line-matrix (TLM) method. An optimum biquadratic shape which reduces the reflections from more than 5% to below 2% in comparison to a linear taper was found. The circuits were measured in the frequency range up to 40 GHz with a wafer prober. At 40 GHz, the insertion loss values were less than 0.4 dB. For a double taper, risetimes of 6.4 ps were achieved which correspond to a bandwidth of 55 GHz;.<>
elib2cris::1512001600,thomann1993
Keywords: time-domain analysis; waveguide couplers; 3D TLM method; Electromagnetic propagation; Bandwidth; Circuit simulation; Shape; Time domain analysis

Characterization In-Situ of Diode Detectors for Six-Port receivers - Barbon, Francesco; Lindner, Stefan; Mann, Sebastian; Linz, Sarah; Weigel, Robert; Kölpin, Alexander (Testmethoden und Zuverlässigkeit von Schaltungen und Systemen (TuZ), 2013)
Six-Port receivers require a precise power mea- surement thus a characterization in-situ of its power detector is necessary. The industrial working ambient requires a constant performance monitoring due to temperature drift, fabrication and component tolerances. The detectors’ performance may have some degradation, which limits the measurement accuracy. Thus, an in-situ detector characterization is necessary. In this paper, a fast and simple solution for estimating the diode detectors’ char- acteristics is presented, which is ideal for Six-Port diode power detectors. This method is fast and can be easily implemented on a microcontroller.
elib2cris::1512001600,barbon2013
Keywords: six-port; diode detector; power measurement; in-situ

Characterization of a 13.56 MHz RF-ID system based on scattering parameters approach - Vinci, Gabor; Sona, Alessandro (Radio and Wireless Symposium, 2009. RWS '09. IEEE, 2009)
The efficient setup and deployment of modern radio frequency identification (RF-ID) systems operating at 13.56 MHz require an accurate knowledge of the reading range associated to the reader unit. To evaluate the reading range, an efficient simulative approach is analyzed in this paper, based on the evaluation of scattering parameters and a computer aided design (CAD) modeling. In particular, a two-port numerical model is considered and the parameter S2,1 analyzed. The purpose is to propose an efficient and original approach, based on S-parameters, in order to characterize an RF-ID system at 13.56 MHz in terms of reading range. Some key working conditions of RF-ID systems are also analyzed in terms of inductive coupling between reader and tag coils.
elib2cris::1512001600,vinci2009
Keywords: RF-ID; Electromagnetic Analysis; Electromagnetic Fields; Electromagnetic Coupling; Scattering Parameters; Coils; Simulation

Characterization of Acoustomigration with On-Wafer Measurement System - Raml, Gerhard; Ruile, Werner; Springer, Andreas; Weigel, Robert (IEEE International Ultrasonics Symposium, 2001)
Developed an automated on-wafer measurement system and a suitable test device for the design-independent characterization of different metallization layers on piezoelectric substrates with respect to acoustomigration. With the measurement system we are able to measure the devices on the wafer without any additional manual handling. The test devices were fabricated on LiTaO3 with Al and AlCu electrodes. The temperature and the applied stress level were kept constant during measurements with the help of our temperature and frequency controlled probing system. The observed reversible and irreversible shift in the test device resonance frequencies originates from self heating and migration in the metal layer, respectively. As a time-to-failure (TTF) criterion an irreversible frequency shift of 1 MHz is defined. The variations of TTF with respect to temperature and power can be interpreted in terms of an Eyring model, which assumes an Arrhenius law for the temperature dependence and a power law dependence for the applied power. As a result it was confirmed that the addition of Cu enhances the power durability of an Al film significantly
elib2cris::1512001600,raml2001
Keywords: Characterization; On-Wafer Measurement; Acoustomigration

Characterization of a Flexible Polymer-Based Substrate Material for RF Applications - Michler, Fabian; Kolpak, Jasmin; Scheiner, Benedict; Weigel, Robert; Hagelauer, Amelie (IEEE Radio and Wireless Symposium (RWS), 2023)

Characterization of an Inductance-based Detector in Molecular Communication Testbed Based on Superparamagnetic Iron Oxide Nanoparticles - Ahmed, Doaa; Unterweger, Harald; Fischer, Georg; Schober, Robert; Kirchner, Jens (IEEE SENSORS 2019, 2019)
Molecular communication (MC), using chemicals or particles, is a promising approach to bridge the gaps of conventional communication systems, e.g. in nano-scale or in pipelines. Our testbed depends on superparamagnetic iron oxide nanoparticles (SPIONs) as information carriers, which are detected using a susceptometer. In this paper, we study how the position and distribution of particles near the susceptometer, i.e., coil, affect its detected signal. When the particles move axially through the coil, an increment in the signal is detected. In addition, we observed a nonlinear additive behaviour of inductance in the same axial direction, i.e., changes in inductance due to partial volumes are not additive. An exponentially-like signal is detected when the particles move radially through the coil. Moreover, a linear additive behaviour of inductance is observed in this direction. Increasing the magnetic susceptibility has a significant effect on the detected signal. However, the susceptibility of SPIONs is relatively small in order to keep superparamagnetic properties. The coil inductance depends not only on the volume, or permeability of magnetic particles in its core, but also on how they are distributed inside. <br
Keywords: molecular communication; superparamagnetic nanoparticles; simulation; MC testbed; coils; magnetic fields

Characterization of SAW Duplexer Inserts for LTCC RF Front-End Modules by Simulation and Measurement - Koch, Robert; Pitschi, Maximilian; Kiwitt, Jürgen; Weigel, Robert (IEEE/MTT-S International Microwave Symposium, 2007, 2007)
The growing demand for miniaturization of mobile terminals incites design engineers to integrate the required functionality of stand-alone active and passive discrete/integrated components of the RF section, such as, e.g., antenna switches, power amplifiers, and SAW filters, into compact modules. Although being a monolithic and complex component in which all sub-systems, formerly stand-alone components, are interlocked, each of them has to be designed and optimized individually and be pieced together in a later step of the development process for the final optimization. Therefore, an efficient design strategy and a neutral test environment for the characterization by both measurement and simulation of the isolated sub-systems are needed. Being able to provide this would allow design engineers to predict reliably the properties of the sub-systems integrated in the target module. In this paper we report on practical and theoretical issues regarding the integration of duplexing functionality into LTCC modules by means of duplexer inserts. Duplexer inserts provide the necessary potential for further height reduction that is required by future developments of modules. One of the key issues that we faced was the precise characterization of the performance of duplexer inserts in the module by both measurement and simulation. We investigated models of different complexity and, therefore, different accuracy and present first experimental results of the characterization of a W-CDMA 2100 duplexer insert. Hereto, we divided the module into its subsystems and applied our new, specifically designed, neutral test/design environments for duplexer inserts in order to evaluate the usability of different approaches. We obtained the best agreement of simulation and measurement for the most complex model.
elib2cris::1512001600,koch2007

Characterization of the wireless onboard channel during tunnel crossing in high-speed rail traffic - Lichtblau, Johann; Lurz, Fabian; Sanftl, Benedikt; Weigel, Robert; Koelpin, Alexander (International Microwave and Optoelectronics Conference (IMOC), 2019)

Chirped SAW devices for wireless passive sensors - Reindl, Leonhard; Rösler, Ulrike; Ruppel, Clemens; Obertreis, Robert; Weigel, Robert (Ultrasonics Symposium, 1997)
Chirped structures as sensing elements in a delay line allow for the variation of the sensitivity over a wide range. A sensor system operating at a center frequency of 434 MHz and a system bandwidth of 1.7 MHz will be shown. We designed dispersive inline SAW structures with two chirped and apodized IDTs. Two expanders, one with an up- and the other with a down-chirp, have been built on quartz 37.5° cut. The corresponding compressors (down- and up-chirp) are the sensor elements and have a wider bandwidth to compensate for the frequency shift due to the sensor effect. The compressors have been built on quartz for mechanical sensing and on LiNbO3, YZ-cut for temperature sensing. To avoid bulk wave conversion we used a modulated IDT with 8 electrodes per electrical period. On quartz we operated these IDTs on the 3rd and on LiNbO3 on the 5th harmonic which is lower than the onset frequency for bulk wave conversion and gives a suitable impedance level as well. We present theoretical and experimental results for the devices and show results of the corresponding sensor systems for temperature.
elib2cris::1512001600,reindl1997a
Keywords: Bandwidth; Chirp; Compressors; Delay lines; Frequency; Mechanical sensors; Sensor systems; Surface acoustic wave devices; Temperature sensors; Wireless sensor networks

Chirp gating enhances performance of chirp spread spectrum systems - Pohl, Alfred; Reindl, Leonhard; Seifert, Franz; Weigel, Robert (IEEE 1998 MTT/AP International Workshop on Commercial Radio Sensor and Communication Techniques, 1998)
The application of chirp spread spectrum systems for a reliable indoor communication system operated in the 2.45 GHz ISM band is shown. A test system have been built applying surface acoustic wave dispersive delay lines (SAW chirp filters) for chirp impulse compression. Gating of a chirp signal and the according compressive device means gating in time and frequency domain simultaneously. If only a part of the chirp is transmitted or received, the impulse compression still delivers useful output signals. This fact can be utilized for transmission of additional data information in chirp gaps with gap position modulation and for leaving out a sub band during transmission, to avoid jamming of other narrowband communication systems operating in this frequency band. It also can be applied for our new method of adaptive interference suppression introduced here. With a tapped dispersive SAW delay line the frequency band for chirp transmission is divided into a number of intervals. If one or some of these sections are occupied, they can be spared out in the transmitter or if a narrowband jammer is received within such subbands, they can be gated and disregarded for the impulse compression. This yields a technique for fast adaptive jamming cancellation without a loss of the simplicity of a SAW based Spread Spectrum system. The experimental system was tested in different electromagnetically polluted indoor areas. Simulations and some preliminary experimental results are presented.
elib2cris::1512001600,pohl1998

Circadian and circaseptan rhythms in implant-based thoracic impedance - Kirchner, Jens; Paule, Stefan; Beckendorf, Claudia; Achenbach, Stephan; Arnold, Martin (Physiological Measurement, 2015)
Thoracic impedance (TI) denotes the electrical resistance that is measured between the right ventricular lead and the can of an implantable cardioverter-defibrillator. It is used in medical diagnostics for fluid load monitoring in heart failure patients. We analysed TI for diurnal and weekly components that go along with the recurrent patterns of daily life. TI was measured in 53 patients over 280d each with a resolution of 1h. Information about the patients' professional occupation and typical sleeping rhythm was sought. Periodic signal components were identified in the amplitude spectrum, and their main characteristics were derived by cosinor analysis. The typical daily and weekly pattern were reconstructed by Fourier filtering. The Fourier spectrum indicates a strong circadian and a weaker circaseptan component in TI. The latter is significantly elevated in patients who regularly go to work, on error level p < 0.05. Cosinor analysis states a significant circadian rhythm in all patients (p < 0.001), with MESOR 61.8Ohm, amplitude 1.9Ohm, and acrophase 17.5h. A significant weekly rhythm is found in 25 patients (p < 0.05), with amplitude 0.31Ohm and acrophase typically on Wednesday. Both rhythms typically obtain their maximum during the 'active' phase of the period in daily life, i.e. in the afternoon and on working days, respectively, while the minimum is reached in the 'recreative' phase. Circadian and circaseptan variation are hence prevalent components of TI, which can induce impedance changes of several Ohms and thus be an error source for daily TI measurements.

Circadian variation in thoracic impedance - Beckendorf, Claudia; Kirchner, Jens; Paule, Stefan; Achenbach, Stephan; Arnold, Martin (Clinical Research in Cardiology Supplements, 2014)
Introduction: Thoracic impedance (TI) is the electrical resistance measured between the right ventricular shock coil and the can of an implantable cardioverter-defibrillator. As it is known to decrease on lung congestion, it has been proposed as a marker of worsening of cardiac status in heart failure patients. However, the diagnostic value of TI is limited by various confounding factors and the extent of physiologic variability is poorly understood. We therefore analyzed circadian variation of TI. Methods: In 54 patients with an implanted ICD (n = 47) or CRT-D (n = 7) device (85% male, 66 ± 11 years, NYHA class I-IV, EF 31 ± 14 %), TI was measured with an hourly resolution. The resulting 24 TI values per day were transmitted via home monitoring. For each patient, data from an observation interval of 28 days were averaged separately for each time of the day. Intra-day variability was correlated to each individual patient´s daily routine, which was determined by a questionnaire. Results: Daily mean thoracic impedance of all 54 subjects was 61.0 ± 6.2 Ω (range: 43.8-71.8 Ω). Intra-day variation was present in all subjects, ranging from 1.1 to 8.4 Ω and with 3.2 ± 1.7 Ω in average. The typical day-curve (see figure) exhibits a clear minimum in the early morning (average lowest TI: -1.9 ± 1.4 Ω below mean) and a plateau in the afternoon (maximum height: 1.3 ± 1.0 Ω above mean). The phases of the day with large changes in TI - nighttime and morning hours till noon - are strongly correlated with the patients going to bed and getting up from bed, respectively: After both events, TI exhibits a trend in negative respectively positive direction (p < 0.001, Page trend test), which leads to significant changes of TI over at least 6 hours (p < 0.001 for all measurement times, Wilcoxon signed-rank test). Figure: circadian variation of the thoracic impedance of a heart failure patient. Conclusion: Thoracic impedance exhibits a strong circadian variation, which amounts to 7 % of its absolute value and seems to be based on the sleep-wake rhythm. Therefore, daily TI values from a single measurement time per day are prone to errors of the same size, particularly when measured in high-dynamic phases. More appropriate is the use of either the mean or an extremal value of the TI day-curve from several equidistant measurement

Circuit Agility - Lourandakis, Errikos; Weigel, Robert; Mextorf, Henning; Knöchel, Reinhard (IEEE Microwave Magazine, 2012)
Over the last decade, mobile communication and its associated mass volume market has become one of the driving forces in the technology evolution of semiconductor and microwave circuits. For handheld communication devices, it is now mainstream to support increasing numbers of communication standards and localization services that occupy ever-expanding wide frequency ranges and bandwidths. At the same time, the physical dimensions of handheld user devices are shrinking, leading to even tighter specifications for the highly integrated front-end architectures of mobile radios. Todays radio front-end architectures use dedicated receive and transmit paths for each covered communication standard, thus the overall complexity and occupied area is increasing as well. The wide frequency allocation of the regulated communication bands along with the variety of standards, which have to be covered by these radios, calls for reconfigurable and frequency agile microwave subsystems. The scope of this article is to provide a comprehensive understanding of design principles for frequency agile and reconfigurable microwave circuits such as power dividers and couplers and how they can be used in radio-frequency (RF)-transceiver subsystems to pave the way toward reconfigurable radio front-end architectures. Introducing reconfigurability in microwave circuits is achieved by tunable passive components. Tunable passives can be implemented in a variety of technologies such as ferroelectric varactors, semiconductor diodes, and microelectromechanical systems (MEMS) components. Attractive applications for tunable circuits in the RF front end are tunable matching networks, filters, reconfigurable power amplifiers, tunable voltage controlled oscillator (VCO) circuits, and finally, couplers and dividers.
elib2cris::1512001600,lourandakis2012
Keywords: microwave circuits; network synthesis; power dividers; waveguide couplers; MEMS component; RF-transceiver subsystem; VCO; circuit agility; communication standard; ferroelectric varactor; frequency agile microwave subsystem; handheld communication device; handheld user device; integrated radio front-end architecture; matching network; microelectromechanical system component; microwave circuit; mobile communication; mobile radio; power amplifier; power coupler; power divider; radio-frequency-transceiver subsystem; semiconductor diode; semiconductor evolution; tunable passive component; voltage controlled oscillator; Agile manufacturing; Communication standards; Integrated circuit layout; Microwave circuits; Mobile communication; Power dividers; Radio spectrum management

Circuit Design for a Radiation Tolerant 2.4 GHz Synthesizer Based on COTS Components - Müller, Steffen; Danzeca, Salvatore; Garcia Alía, Rubén; Brugger, Markus; Weigel, Robert; Kölpin, Alexander (IEEE Topical Workshop on Internet of Space (TWIOS), 2018)

Circuit Design for Common-mode Noise Rejection in Biosignal Acquisition based on Imbalance Cancellation of Electrode Contact Resistance - Chen, Minghui; Anzai, Daisuke; Wang, Jianqing; Fischer, Georg (EMC Sapporo & APEMC 2019, 2019)
Common-mode (CM) noise is a primary interference to biological signal (biosignal) detection systems but is hardly solved with passive filtering. Conventionally, a driven-right-leg (DRL) circuit is employed to drive down the CM noise level. In this paper, we proposed a novel design of biosignal acquisition circuit based on canceling the imbalance between contact resistances of detection electrodes and made a comparison with the DRL circuit. We first theoretically analyzed how it works in rejecting the CM noise. Then we conducted circuit simulation and the result indicates that our design could realize a common-mode rejection of as high as 200 dB in experimental condition, which is better than the simulated DRL circuit. <br
Keywords: ECG; electrode; contact impedance

Circuits with Scaled Metal Oxide Technology for Future TOLAE RF Systems - Schrüfer, Daniel; Ellinger, Martin; Jank, Michael; Frey, Lothar; Weigel, Robert; Hagelauer, Amelie Marietta (Proceedings of the 48th European Microwave Conference, 2018)
A novel architecture for thin-film transistors (TFT) utilising the concept of combining a staggered and a coplanar electrode in a single Alternating Contact TFT (ACTFT) is presented. It exhibits a transit frequency of 49.2MHz for a channel length of 0.6 μm at a drain and gate voltage of 2V. Based on these ACTFTs various n-channel-only digital circuits were fabricated and are presented here.<br
Keywords: Thin film devices; thin film circuits; logic circuits; logic gates

Circular Gysel Divider for the Frequency Range from 18 GHz to 26 GHz - Gabsteiger, Jasmin; Beck, Christopher; Dietz, Marco; Weigel, Robert; Lurz, Fabian (2022 52nd European Microwave Conference, EuMC 2022, 2022)
Power dividers are required and used in a wide variety of applications. It is often sufficient to halve the power and divide it evenly between two branches. However, if one branch requires more power than the other, a divider with an unequal power ratio is needed. In the presented work, an equal and an unequal Gysel divider were designed, simulated and measured. Compared to other Gysel splitters, the ones demonstrated here have advantages in size, isolation and losses.
CRIS-Team Scopus Importer:2022-12-02
Keywords: Gysel divider; power divider; unequal

Closing the Gap between the Multichannel and the Stereo Audio World: Recent MP3 Surround Extensions - Grill, Bernhard; Hellmuth, Oliver; Hilpert, Joe; Herre, Jürgen; Plogsties, Jan (120th AES Convention, 2006)
Vorträge und Veröffentlichungen auf Konferenzen_Mehrkanalige Codierung von Audiosignalen

CMOS and SAW RFID Tags at UHF Frequencies - Weigel, Robert; Seemann, Kay; Reindl, Leonhard (Third International Symposium on Acoustic Wave Devices for Future Mobile Communication Systems, 2007)
Today, there exists a huge market pull towards radio frequency identification (RFID) and/or wireless sensing for high-volume applications as well as for profesional applications based on the use of passive, i.e., battery-less, low-cost transponders (tags, labels). In order to arrive at smaller tag dimensions, higher transceiver-to-tag interdistances, and more flexible, i.e., application-dependent antenna desings, higher-than-LF/HF carrier frequencies in the UHF band are becoming extremely interesting. CMOS and SAW transponder technologies are of special interest while other technologies such as polymer-electronic RFID tags re not feasible for the use in today's applications. In what follows, we weill report on the current status and future trends of both CMOS and SAW RFID backscatter techniques.
elib2cris::1512001600,weigel2007
Keywords: Passive RFID transponders; CMOS tags; SAW tags; SAW sensors; RFID systems; RFID radar transceivers

CMOS RF Switch with Fast Discharge Feature - Solomko, Valentyn; Özdamar, Oguzhan; Weigel, Robert; Hagelauer, Amelie (IEEE Solid-State Circuits Letters, 2021)
A radio-frequency (RF) switch featuring a circuit for fast discharge of the gate oxide capacitance is presented in the paper. Two auxiliary transistors are added between the gate and source/drain terminals of the main switch. They are brought into ON state for a short time at the beginning of the switching transient, discharging the gate of the main transistor and speeding up the switching process. An integrated circuit implementing the proposed concept based on a large shunt switch has been designed and fabricated in Infineon 130nm bulk-CMOS RF-switch technology. The measurements have demonstrated improvement in switching time (defined as time between the control signal trigger edge and 90% of the target RF amplitude) of above 50% with no penalty in RF performance comparing to the conventional switch without discharge feature. The measured OFF-state insertion loss and ON-state isolation at 824MHz were 0.12 dB and 27.2 dB respectively.<br
Keywords: antenna tuning; cellular user equipment; fast switching; harmonics; high-voltage switch; switching time acceleration

CMOS Signalverarbeitung im Basisband für Sensornetzwerke mit Lokalisierungsfunktion - Jung, Melanie; Ferizi, Alban; Weigel, Robert (RADCOM, 2010)
elib2cris::1512001600,jung2010

CO2 sensor for mainstream capnography based on TDLAS - Hartmann, Alexander; Strzoda, Rainer; Weigel, Robert (Applied Physics B-Lasers and Optics, 2014)
elib2cris::1512001600,hartmann2014

Cognitive Multi-Radio as Enabler for Deterministic Dynamic Spectrum Access - Kloc, Matej; Franchi, Norman; Gardill, Markus; Weigel, Robert (Wireless Innovation Forum European Conference on Communication Technologies and Software Defined Radio (WInnComm-Europe), 2015)
Cognitive radio (CR) is a promising approach to enable dynamic spectrum access (DSA) and to handle spectral efficiency in licensed frequency bands. In this presentation, two new concepts, called cognitive multi-radio (CMR) and deterministic dynamic spectrum access (D-DSA), are introduced. These concepts help to increase the spectrum agility and hence to improve the deterministic broadband spectrum access in unlicensed industrial, medical and scientific (ISM) bands, where shared spectrum lead to interferences and/or collisions, which consequently degrade transmission performance. Here, the CMR-based D-DSA approach is discussed in context with industrial wireless communications (IWC), where a real-time capable transmission behavior with high determinism, high reliability and low-latency (round-trip latency budget ≤ 1 ms) is required. In addition, a CMR hardware architecture, which is based on the software-defined radio (SDR) principle, is proposed.
elib2cris::1512001600,kloc2015

Cognitive PMSE for Spectrum Sharing at UHF - Fischer, Georg; Brendel, Johannes; Rieß, Steffen (Wireless Innovation Forum (SDR Forum Version 2.0), Conference on Communication Technologies and Software Defined Radio WINCOMM, 2015)
This talk reports about work in ETSI STF386 pre-standardisation and a German national Research Project by BMWI named C-PMSE dealing with cognitive interference management to allow for coexistance of PMSE, DVB-T and LTE at UHF Band.
elib2cris::1512001600,fischer2015a
Keywords: SDR; PMSE; C-PMSE; CR; UHF

Cognitive Systems for the Professional Audio Industry: a Step Forward - Fischer, Georg; Perez-Guirao, M.; Bilz, W.; Reihl, E.; Circa, R.; Schmidt, Axel (6th Karlsruhe Workshop on Software Radios, 2010)
elib2cris::1512001600,fischer2010

Coherent Time Difference of Arrival Estimation Techniques for Frequence Hopping GSM Mobile Radio Signals - Götz, Alexander (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2013)

Colour-Specific Microfluidic Droplet Detection for Molecular Communication - Bartunik, Max; Fleischer, Marco; Haselmayr, Werner; Kirchner, Jens (Proceedings of the 7th ACM International Conference on Nanoscale Computing and Communication, 2020)
Droplet-based microfluidic systems are a promising platform for lab-on-a-chip (LoC) applications. These systems can also be used to enhance LoC applications with integrated droplet control information or for data transmission scenarios in the context of molecular communication. For both use-cases the detection and characterisation of droplets in small microfluidic channels is crucial. So far, only complex lab setups with restricted capabilities have been presented as detection devices. We present a new low-cost and portable droplet detector. The device is used to confidently distinguish between individual droplets in a droplet-based microfluidic system. Using on-off keying a 16-bit sequence is successfully transmitted for the first time with such a setup. Furthermore, the devices capabilities to characterise droplets regarding colour and size are demonstrated. Such an application of a spectral sensor in a microfluidic system presents new possibilities, such as colour-coded data transmission or analysis of droplet content.<br
Keywords: droplet detection; microfluidic environment; molecular communication; colour; optical sensor

Combined frequency domain feedforward and turbo decision feedback equalization for single carrier W-LAN systems - Koppler, Alois; Springer, Andreas; Weigel, Robert (IEEE International Conference on Communications, 2003)
Single carrier transmission with frequency domain equalization (SC/FDE) has been shown to be a promising alternative to orthogonal frequency division multiplexing (OFDM) systems for wireless LANs. In this work we add time domain turbo decision feedback equalization to conventional SC/FDE for block transmission with cyclic prefix. The proposed scheme achieves the potential of ideal decision feedback equalization. Simulation results show a considerable performance increase for highly frequency selective radio channels given in W-LAN environments.
elib2cris::1512001600,koppler2003a

Combined Galileo/GPS architecture for enhanced sensitivity reception - Schmid, Andreas; Neubauer, André; Ehm, Henning; Weigel, Robert; Lemke, Norbert; Heinrichs, Günther; Winkel, Jón; Avila-Rodriguez, Jose-Angel; Kaniuth, Roland; Pany, Thomas; Eissfeller, Bernd; Rohmer, Günther; et al. (AEÜ - International Journal of Electronics and Communications, 2005)
Several new requirements and challenges are introduced with the transition of traditional navigation applications towards location-based services (LBSs). This paper introduces the HIGAPS receiver concept. Aim of the HIGAPS project is to develop the concept for a combined Galileo/GPS receiver that is specially tailored for LBSs, E-911, and other consumer market applications. After a brief overview of the receiver, the partitioning into analog hardware, digital hardware, and software is outlined. The architecture of the combined Galileo/GPS RF front-end is presented in low-IF topology. The digital baseband presents a highly parallel correlation architecture for combined Galileo/GPS reception, allowing fast times to fix for extended dwell times. Parallel digital signal processing combined with aiding data allows single-shot measurements particularly designed for LBSs. Differential correlation further improves the reception sensitivity. The coherently integrated predetection samples are thereby multiplied with the conjugated complex previous predetection samples.
elib2cris::1512001600,schmid2005
Keywords: Galileo; GPS

Combined linear programming/belief propagation decoder - Lunglmayr, Michael; Berkmann, Jens; Huemer, Mario (Electronics Letters, 2008)
For decoding of LDPC codes two types of algorithms are frequently discussed in the literature. One type is based on belief propagation (BP) the other is based on linear programming (LP). Especially for short LDPC codes it has been observed that BP decoding often performs better at low SNR ranges, whereas LP decoding performs better at high SNR levels. A combined linear programming and belief propagation decoder is presented, which significantly outperforms both a pure LP and a pure BP decoder throughout the whole SNR range.
elib2cris::1512001600,lunglmayr2008a

Combined Localization and Data Transmission in Energy-Constrained Wireless Sensor Networks - Nowak, Thorsten; Kölpin, Alexander; Dressler, Falko; Hartmann, Markus; Patino-Studencki, Lucila; Thielecke, Jörn (IEEE Topical Conference on Wireless Sensors and Sensor Networks, 2015)
UnivIS-Import:2015-04-17:Pub.2015.tech.IE.komele.combin

Combining Radar and Communication at 77 GHz Using a CDMA Technique - Lübke, Maximilian; Fuchs, Jonas; Shatov, Victor; Dubey, Anand; Weigel, Robert; Lurz, Fabian (2020 IEEE MTT-S International Conference on Microwaves for Intelligent Mobility (ICMIM), 2020)

Commercial and Scientific Solutions for Blood Glucose Monitoring—A Review - Xue, Yirui; Thalmayer, Angelika; Zeising, Samuel; Fischer, Georg; Lübke, Maximilian (Sensors, 2022)

Commissioning And First Beam Measurements With A New Beam Diagnostics For Medical Electron Accelerators - Vlad, Daniel; Fischer, Georg; Hänel, Marc (Proceedings of the International Particle Accelerator Conference, 2014)
elib2cris::1512001600,vlad2014

Common-mode noise reduction circuit design for biosignal acquisition system-in comparison with the DRL - Chen, Minghui; Wang, Jianqing; Anzai, Daisuke; Fischer, Georg (IEEJ Transactions on Fundamentals and Materials, 2019)
Common-mode (CM) noise is a primary interference to biological signal (biosignal) detection systems, but is hardly solved with passive filtering. Conventionally, a driven-right-leg (DRL) circuit is employed to drive down the CM noise level. In this work, We first clarified how much influence an imbalance in the contact resistance could have for three different kinds of circuits, and then proposed a novel design of imbalance cancellation circuit using the digital potentiometer(digiPOT). Simulation evaluations were performed and the results showed that our circuit design can exceed the DRL by more than 20 dB in reducing the CM noise under the same conditions.
CRIS-Team Scopus Importer:2019-12-17
Keywords: Biosignal acquisition; Biosignal sensing; Common-mode noise; Electromagnetic compatibility; Electromagnetic interference; EMC

Common-Mode Noise Reduction in Noncontact Biopotential Acquisition Circuit Based on Imbalance Cancellation of Electrode-Body Impedance - Chen, Minghui; Wang, Jianqing; Anzai, Daisuke; Fischer, Georg; Kirchner, Jens (Sensors, 2020)
Biopotential sensing technology with electrodes has a great future in medical treatment and human—machine interface, whereas comfort and longevity are two significant problems during usage. Noncontact electrode is a promising alternative to achieve more comfortable and long term biopotential signal recordings than contact electrode. However, it could pick up a significantly higher level of common-mode (CM) noise, which is hardly solved with passive filtering. The impedance imbalance at the electrode–body interface is a limiting factor of this problem, which reduces the common mode rejection ratio (CMRR) of the amplifier. In this work, we firstly present two novel CM noise reduction circuit designs. The circuit designs are based on electrode-body impedance imbalance cancellation. We perform circuit analysis and circuit simulations to explain the principles of the two circuits, both of which showed effectiveness in CM noise rejection. Secondly, we proposed a practical approach to detect and monitor the electrode-body impedance imbalance change. Compared with the conventional approach, it has certain advantages in interference immunity, and good linearity for capacitance. Lastly, we show experimental evaluation results on one of the designs we proposed. The results indicated the validity and feasibility of the approach.<br
Keywords: biomedical electronics; common-mode noise; electromagnetic interference; noncontact electrode

Communication ICs — market leaders in microelectronics - Stelzer, Andreas; Weigel, Robert (Elektrotechnik und Informationstechnik, 2001)
In recent years communication ICs became the fastest growing semiconductor market segment mainly driven by personal wireless communication products like pagers or mobile phones and internet applications with their permanent demand on increasing bandwidth. The high volume consumer market and its demand for low-cost, low-power, and highly integrated solutions had stimulated RF design engineers all over the world to develop novel integrated solutions for communication devices with an innovative advance that is more close to Moore’s law than it was in the past. This was made possible once by a great progress in semiconductor technology, where well established silicon and silicon bipolar technologies extend the operating range steadily up to higher frequencies in the GHz range at the expense of GaAs technology which is driven back to niche products like power amplifiers and to communication techniques in the 40-Gbits/s range and above. On the other hand the integration of a complete system with a single technology has also consequences to the topology of the system and that has led to fundamental changes in system design procedures, which are treated by more sophisticated design tools which cover both system and circuit design and bring them close together. In this paper some actual trends in the development of communication ICs are presented and examples of recently published devices are given.
elib2cris::1512001600,stelzer2001a
Keywords: circuit-design; development tools; GaAs; bipolar; silicon technology; system development; communication IC; semiconductor industry

Compact 2-28 GHz Planar Multi-Octave Bandwidth Wilkinson Power Dividers - Trenz, Florian; Hofmann, Maximilian; Weigel, Robert; Fischer, Georg; Kissinger, Dietmar (2014 IEEE MTT-S International Microwave Symposium (IMS), 2014)
In this paper, two broadband Wilkinson power dividers in microstrip technology are presented. A broadband operation from 2 to 28 GHz could be achieved by a multisectional layout. The dividers differ in the number of cascaded steps, which allows application dependent usage. Furthermore, the dividers make use of commercially available, surface mounted thinfilmresistors, allowing a straightforward implementation. The maximum occupied area is around 30mm2 for the longer version and around 16mm2 for the shorter version. Measurements show a matching better than 13 dB and an isolation of better than 10 dB over the whole frequency range. The achieved bandwidth ratio of 14:1 represents, in combination with the compact layout, the highest ratio for Wilkinson dividers published so far.
elib2cris::1512001600,trenz2014
Keywords: Wilkinson power divider; broadband

Compact Low-cost Substrate Integrated Waveguide Fed Antenna for 122 GHz Radar Applications - Frank, Martin; Lurz, Fabian; Weigel, Robert; Kölpin, Alexander (International Journal of Microwave and Wireless Technologies, 2019)

Compact PCB Delay Line for Six-Port Based Instantaneous Frequency Measurement - Lurz, Fabian; Scheiner, Benedict; Linz, Sarah; Weigel, Robert; Kölpin, Alexander (22nd International Microwave and Radar Conference (MIKON), 2018)

Compact polarimetry for automotive applications - Erhart, Christian; Lutz, Steffen; Mutschlerl, Marc A.; Scharf, Philipp A.; Walter, Thomas; Mantz, Hubert; Weigel, Robert (International Journal of Microwave and Wireless Technologies, 2019)
Though compact polarimetric approaches have been developed and applied in space and geo researching systems they have not been taken into consideration in automotive applications, yet. A sensor system has been designed to conduct polarimetric measurements in the 77 GHz frequency band, which is permitted for automotive usage. This system is able to transceive linearly as well as circularly polarized electromagnetic continuous waves. Depending on the case of application, the frequency output can be set statically or modulated over time within adjustable parameters. Hence, a variety of compact polarimetric modes can be performed and compared with full polarimetric approaches. Two compact polarimetric modes, dual-circular polarimetric mode, and circular-transmit-linear-receive, will be introduced and applied in this contribution. Their operability in this frequency range will be investigated after the microstrip antennas as well as the beam focusing dielectrical lense are characterized. Finally, results of a realistical measurement set-up will confirm the practicability of compact polarimetric approaches for double bounce recognition.
CRIS-Team WoS Importer:2019-04-12

Compact Scan-Phase Antenna Diversity Related System Considerations - Senega, Simon; Röber, Jürgen; Nassar, Ali; Weigel, Robert; Heuer, Christian; Lindenmeier, Stefan (European Microwave Week, 2016)
An integrated antenna diversity system is described which enables a high increase of reception performance for satellite digital audio radio services (SDARS). A detailed analysis is given for the gain and noise figure requirements specifically regarding the implementation in an integrated circuit. In this contribution a compact integrated diversity system is specified and its realization is described. Also sufficient immunity to high level interferers must be ensured which can be in close proximity as far as frequency distance is concerned. On base of the specified values the system provides an overall gain of 26.8 dB with a noise figure of 0.84 dB including the single rf cable connecting the diversity antenna set to the unmodified standard SDARS receiver. A hardware demonstrator of our scan-phase antenna diversity system is presented in which the phase aligned rf combining and signal selection is implemented in a compact IC with a package size of only 8mm by 8 mm. Measurement results with recorded Rayleigh fading signals from a test drive in the US with a duration of 290 s show a reduction of audio mutes from 29.8 s of the best single antenna to only 4.1 s with our scan-phase antenna diversity demonstrator.
elib2cris::1512001600,senega2016

Comparative Analysis of High-Frequency Transitions in Embedded Wafer Level BGA (eWLB) and Quad Flat no Leads (VQFN) Packages - Seler, Ernst; Wojnowski, Maciej; Sommer, Grit; Weigel, Robert (IEEE 14th Electronics Packaging Technology Conference (EPTC), 2012)
Embedded Wafer Level Ball Grid Array (eWLB) is one of the most advantageous packaging technologies with respect to higher I/O density, process easiness, integration flexibilities and electrical performance. When it comes to high-frequency (HF), the latter has to be considered particularly. The Quad Flat no Leads Package (VQFN) has often been the choice due to good HF-performance. We present the comparison of the two package technologies eWLB and VQFN. In this paper we present an optimized 24 GHz chip-package-board transition. We compare the performance of an eWLB package to a VQFN package. We focus on a single-ended transition. We obtain a simulated insertion loss better than -0.5 dB in eWLB compared to -1.5 dB in VQFN. In this contribution we show the outstanding potential of the eWLB package for mm-wave applications.
elib2cris::1512001600,seler2012
Keywords: ball grid arrays; wafer level packaging; HF-performance; I-O density; VQFN packages; chip-package-board transition; eWLB package; embedded wafer level BGA; electrical performance

Comparative Evaluation of a New Sensor for Superparamagnetic Iron Oxide Nanoparticles in a Molecular Communication Setting - Bartunik, Max; Unterweger, Harald; Alexiou, Christoph; Schober, Robert; Lübke, Maximilian; Fischer, Georg; Kirchner, Jens (EAI BICT 2020 - 12th EAI International Conference on Bio-inspired Information and Communications Technologies, 2020)
Testbeds are required to assess concepts and devices in the context of molecular communication. These allow the observation of real-life phenomena in a controlled environment and therefore present the basis of future work. A testbed using superparamagnetic iron oxide nanoparticles (SPIONs) as information carriers was constructed with regard to this context and requires a sensitive receiver for the detection of SPIONs. This paper focusses on the comparison between a newly presented device (inductance sensor), a previously constructed SPION sensor (resonance bridge), and a commercial susceptometer as reference. The new inductance sensor is intended to improve on a low sensitivity achieved with the previous device and restrictions with respect to sample rate and measurement aperture encountered with the susceptometer. The signal-to-noise ratio (SNR) for each device is assessed at a variety of SPION concentrations. Furthermore, the sensors bit error rates (BER) for a random bit sequence are determined. The results show the device based on an inductance sensor to be the most promising for further investigation as values both for BER and SNR exceed those of the resonance bridge while providing a suciently high sample rate. On average the SNR of the new device is 13 dB higher while the BER for the worst transmission scenario is 9% lower. The commercial susceptometer, although returning the highest SNR, lacks adaptability for the given use case.<br
Keywords: Molecular Communication; Superparamagnetic Iron Oxide; Nanoparticles; SPION; Testbed; Susceptometer; Resonance Bridge; Inductance Sensor; SNR; BER

Comparative Evaluation of Different Current Saving Strategies for Power Amplifiers in Back-Off Operation - Pinarello, Sandro; Müller, Jan-Erik; Weigel, Robert (European Microwave Conference (EuMC), 2013)
Three different methodologies are compared, which are suitable for saving battery current of a power amplifier operated in back-off. Dynamic Voltage Biasing (DVB), Dynamic Current Biasing (DCB), and Load Modulation (LM) have been paired in three different ways and experimentally tested for the first time on the same power transistor to achieve meaningful conclusions. Measurement results from on-wafer load-pull investigation of a SiGe power cell identify the combination of DVB and DCB as the most profitable strategy. This mode manifests a power added efficiency higher than 75% for an excellent 14dB back-off dynamic.
elib2cris::1512001600,weigel2013a
Keywords: modulation; power amplifiers; power transistors; DCB; DVB; LM; back-off operation; battery current; current saving strategies; dynamic current biasing; Digital video broadcasting; Frequency measurement

Comparing mmWave Channel Simulators in Vehicular Environments - Lübke, Maximilian; Dimce, Sigrid; Schettler, Max; Lurz, Fabian; Weigel, Robert; Dressler, Falko (2021 IEEE 93rd Vehicular Technology Conference, 2021)

Comparison of Channel Estimation Techniques for a Single Carrier System Using Frequency Domain Equalization and a Similar Hiperlan/2-Like OFDM System - Koppler, Alois; Weigel, Robert; Huemer, Mario; Witschnig, Harald (International Workshop on Multi-Carrier Spread Spectrum and Related Topics, 2001)
In this work we compare the performance of a single carrier system with frequency domain equalization (SC/FDE) with an OFDM (Orthogonal Frequency Division Multiplexing) system as described in the Hiperlan/2 and IEEE 802.11a standards. The SC/FDE concept proves to have a couple of similarities to OFDM systems in terms of cyclically extended transmit blocks, frequency domain processing, and more. In our proposed single carrier system [1] as well as in Hiperlan/2-like OFDM systems, an estimation of the channel transfer function is needed for equalization purposes. We present different frequency domain based channel estimation techniques for both applications which are quite comparable. Simulations have been done for channel-coded data in typical indoor multipath environments delivering BER-curves. Our results indicate that the proposed concepts achieve similar bit error rate performances for both systems while efficient channel estimation is by far less complex for the SC/FDE system. Moreover, the analog hardware requirements are much more moderate for the SC/FDE system compared to OFDM systems.
elib2cris::1512001600,koppler2001b
Keywords: Channel Estimation; Single Carrier System; Frequency Domain Equalization; OFDM

Comparison of class A and class D RF amplifier operation with focus on reverse intermodulation and efficiency performance - Kamper, Michael; Ulbricht, Gerald; Weigel, Robert; Fischer, Georg (European Microwave Integrated Circuits Conference, 2011)
A Current Mode Class D (CMCD) power amplifier at 900 MHz is presented. After a theoretical analysis, a class D amplifier is designed, simulated and afterwards assembled and characterized. Thereby, a maximum drain efficiency of 80.6%, and a maximum power added efficiency (PAE) of 72.8% at a switching frequency of 864 MHz, and an output power of 28.2 dBm were obtained. A linear class A amplifier using the same transistor exhibits a drain efficiency of 48.9% and 48.0% PAE at a comparable output power. An analysis of the reverse intermodulation distortion (IMD) of the switched-mode class D amplifier in comparison to the class A amplifier shows a 15dB improvement of the third order intermodulation ratio. To the authors' knowledge, this is the first practical verification of the superior reverse intermodulation performance of switched-mode amplifiers.
elib2cris::1512001600,kamper2011
Keywords: UHF power amplifiers; current-mode circuits; intermodulation distortion; radiofrequency amplifiers; current mode class D power amplifier; reverse intermodulation distortion

Comparison of different Semiconductor Technologies for RF Power Transistors for use within Basestation Amplifiers - Friedel, Bernd; Eckl, Wolfgang; Fischer, Georg (Workshop on RF and baseband Architectures for future reconfigurable Multiband/Multistandard Basestations and Terminals, 2003)
elib2cris::1512001600,friedel2003

Comparison of Filterbanks for High Quality Audio Coding - Brandenburg, Karlheinz; Eberlein, K; Herre, Jürgen; Edler, Bernd (IEEE ISCAS, 1992)
Eingeladene Vorträge auf Konferenzen etc.

Comparison of gm-boosted oscillators in silicon field effect transistor and silicon-germanium hetero-junction bipolar transistor technology - Ußmüller, Thomas; Seemann, Kay; Weigel, Robert (Wireless Technology Conference, 2009. EuWIT 2009. European, 2009)
This paper presents two gm-boosted VCOs. One VCO is built with Si MOS field effect transistors. The second one is built with SiGe bipolar transistors. Both VCOs are designed to cover a large tuning range from 5.2 GHz to 5.9 GHz and to minimize the power dissipation. Measured results for both oscillators are shown. Finally the performance of both oscillators is compared and analyzed.
elib2cris::1512001600,ussmueller2009b
Keywords: CMOS analog integrated circuits; Microwave FET oscillators; Microwave integrated circuits; Microwave oscillators; Monolithic integrated circuits; Voltage controlled oscillators

Comparison of IBIS Behavioral Driver Models and the According Transistor Based Models Under Varying Loads - Frank, Florian; Steinmair, Gernot; Weigel, Robert (International Workshop on Electromagnetic Compatibility of Integrated Circuits, 2005)
elib2cris::1512001600,frank2005
Keywords: IBIS; EMC

Comparison of One- and Two-dimensional Slow Fading Models in Mobile Radio System Simulations - Osterkorn, Christian; Ostermayer, Gerald; Huemer, Mario (Annual International Symposium on Personal Indoor and Mobile Radio Communications, 2005)
This paper investigates the behavior of two different slow fading models in cellular mobile radio systems. A one-dimensional and a two-dimensional model are compared with respect to their influence on the results of system level simulations for cellular systems. A disadvantage of most known slow fading models is that they cannot handle the correlation behavior of shadowing in two dimensions. Recently a new model, which provides a two-dimensional correlation property, was proposed by Cai and Giannakis (2003). We show that this model gives different results for system capacity and handover rates than the well known one-dimensional models
elib2cris::1512001600,osterkorn2005
Keywords: Base station; fading

Comparison of time domain package characterization techniques using TDR and VNA - Engl, Mario; Eurskens, Wolfram; Weigel, Robert (Electronics Packing Technology Conference, 2004)
As operating frequencies rise and supply voltages decrease, the electrical performance of packages becomes more and more important. Hence, parasitic effects and electrical characterization of packages play an important role for todays and future applications. In this paper, we describe a state-of-the-art Time Domain Reflectometry measurement technique and evaluate its applicability tn package characterization. Furthermore, we compare the results obtained from a conventional Time Domain Reflectometer (TDR) with that of a Vector Network Analyzer fVNA). Since the VNA is actually operating in frequency domain, its results are transformed to time domain. As test samples, several packages containing integrated circuits with defined standards like short, open and load were measured. The results show that Time Domain Reflectometry techniques are well suited for failure analysis and package characterization. Besides it turned out that the results from the VNA are superior.
elib2cris::1512001600,engl2004a

Comparison of Various Hardware Architectures for the Shared UE-Side Distributed Antenna Component - Ali, Arslan; Fischer, Georg; Burkhardt, Frank; Breiling, Marco (2018 IEEE International Symposium on Dynamic Spectrum Access Networks (DySPAN) - Workshop: 5G and Spectrum Sharing (5G Spectrum), 2018)
Shared UE-side Distributed Antenna System (SUDAS) is a very promising technique in order to deliver an improved coverage and high throughput beyond 10 Gbit/s to the users in the indoor and intra-vehicular scenarios for 5G applications. This paper presents an implementation perspective and comparison analysis of different candidate hardware architectures suitable for the Shared UE-side Distributed Antenna Component (SUDAC), which is the main building block of the SUDAS and acts as a relay and performs massive spatialto-frequency domain translation and vice versa. Based on the defined comparison criteria and scoring of different architectures, it has been established that Analog SUDAC with Slight Frequency Shifting (SFS), Analog SUDAC with Digital Control, Digital SUDAC with 802.11ad and Digital SUDAC with Frequency Domain Equalization (FDE) are the top candidates for hardware implementation and future deployment. <br
Keywords: 5G mobile communication; frequency domain equalization; mmWave communication; relay communication; transceiver architectures; virtual MIMO

Complex-Valued Neural Networks for Millimeter Wave FMCW-Radar Angle Estimations - Kaiser, Kevin; Daugalas, Jonas; Lopez-Randulfe, Javier; Knoll, Alois; Weigel, Robert; Lurz, Fabian (2022 19th European Radar Conference, EuRAD 2022, 2022)
Processing radar signals with neural networks has shown promising results in classification and regression tasks. While processed radar data is intrinsically complex-valued, most architectures using neural networks are comprised of real-values and their arithmetic. Previous work has found that keeping the complex-valued number system and extending it into the domain of neural networks can be beneficial. In this paper, we demonstrate that in two-dimensional direction-of-arrival (DoA) estimation, complex-valued neural networks (CVNNs) show better results than real-valued neural networks (RVNNs). Real-world recordings of ten different FMCW radar devices were used to train numerous models, varying in the computational complexity and varying in data properties. Over all models trained, the best CVNN surpassed the best RVNN by 14%. In terms of model complexity, CVNNs also showed better results, both per trainable parameter and per floating point operation (FLOP). Similarly, CVNNs surpass RVNNs, both when trained with decreased data quantity and decreased data quality.
CRIS-Team Scopus Importer:2022-11-25
Keywords: computational complexity; machine learning; millimeter wave radar; neural networks

Components and Implementation of a Spectrum Sensing Network for the UHF TV Band - Rieß, Steffen; Brendel, Johannes; Stöckle, Andreas; Rose, Richard; Fischer, Georg (European Microwave Conference (EuMC), 2013)
Spectrum sensing is a major part for the implementation of Cognitive Radio (CR) systems in order to enable dynamic access to the radio frequency spectrum. This paper is about a Spectrum Sensing Network (SSN) which generates an accurate radio environment map (i.e. power over frequency, time and location) in the UHF TV band from 470–870 MHz. It consists of a distributed network of multiple receivers with a broadband antenna and a central data management and storage unit. This contribution focuses on the implementation of such a scanning network which has been setup as universal research platform in several halls at the fairground in Berlin. The SSN itself is part of a complex CR system for Professional Wireless Microphone Systems (PWMS) that is able to provide a dynamic frequency allocation of the connected radio links.
elib2cris::1512001600,riess2013

Compressed sensing based near-field radar target imaging and localization employing normalized iterative hard thresholding - Reißland, Torsten; Lurz, Fabian; Weigel, Robert; Kölpin, Alexander (IEEE Topical Conference on Wireless Sensors and Sensor Networks (WiSNet), 2019)
The paper presents an approach for target position recovery from frequency modulated continuous wave (FMCW) radar data. The presented algorithm is, in contrast to many established techniques, able to use snapshots taken from arbitrary positions. The presented technique can be applied to imaging as well as localization applications. The basis of the approach is a compressed sensing based algorithm called normalized iterative hard thresholding (NIHT). To prove its capabilities it is evaluated by simulation over a wide range of signal bandwidths and base frequencies.
Keywords: radar; compressed sensing; imaging; localization; niht

Concentration detection in water-glucose mixtures for medical applications using ultrasonic velocity measurements - Schwerthöffer, Udo; Winter, M.; Weigel, Robert; Kissinger, Dietmar (IEEE Internation Symposium on Medical Measurement and Applications, 2013)
elib2cris::1512001600,schwerthoeffer2013

Concept and Implementation of a Scanning Receiver - Rieß, Steffen; Spratler, Christian (C-PMSE Final Workshop, 2013)
elib2cris::1512001600,riess2013b

Concept for a CMOS Image Sensor Suited for Analog Image Pre-Processing - Shi, Lan; Söll, Christopher; Bänisch, Andreas; Weigel, Robert; Seiler, Jürgen; Ußmüller, Thomas (DATE Friday Workshop on Heterogeneous Architectures and Design Methods for Embedded Image Systems, 2015)
A concept for a novel CMOS image sensor suited for analog image pre-processing is presented in this paper. As an example, an image restoration algorithm for reducing image noise is applied as image pre-processing in the analog domain. To supply low-latency data input for analog image preprocessing, the proposed concept for a CMOS image sensor offers a new sensor signal acquisition method in 2D. In comparison to image pre-processing in the digital domain, the proposed analog image pre-processing promises an improved image quality. Furthermore, the image noise at the stage of analog sensor signal acquisition can be used to select the most effective restoration algorithm applied to the analog circuit due to image processing prior to the A/D converte

Concept for a time-code signal assisted single-shot receiver - Kandziora, Christoph; Weigel, Robert (IEEE Topical Conference on Wireless Sensors and Sensor Networks, 2011)
This paper presents a novel concept for a GNSS receiver for mobile devices based on the single-shot receiver concept. In comparison to the common single-shot receiver the amount of computational hardware is significantly reduced by an estimation of the time of signal reception. This allows an a-priori estimation of the code-phase of the satellites in view. The synchronisation to the time code signal must be better than 1 ms for GPS-In-Orbit-Vehicles(IOVs) to take effect which is here realized by using the german DCF77 signal with an precision of 250 ns under ideal circumstances. Regarding all uncertainties in time and the amount of signal processing power required for the time synchronisation the computational effort for the advanced single-shot receiver can be cut down by a factor of two.
elib2cris::1512001600,kandziora2011

Concept For Electronic Calibration Of A CMOS Voltage Reference - Heinrich, Matthias; Heidrich, Jürgen; Ußmüller, Thomas; Weigel, Robert (IEEE International Conference on Wireless Information Technology and Systems, 2010)
In this paper an approach for a CMOS voltage reference with the ability to calibrate both voltage over temperature behavior and absolute voltage value is presented. This is achieved by electronic controlled trimming of resistances in the PTAT current source and output amplifier. For the transistors in the PTAT current source, the diode connected reference source and the error amplifier a common size of width W = 1μm and length L = 4μm was chosen. The design has a nominal total current consumption of 3.4μA and operates at a minimum supply voltage as low as 800mV for the chosen Vref2 of 700mV. The design can be optimized for even lower current consumption by using higher resistances as well as narrower and/or longer transistors. However, such an adaption increases the chip area due to the larger size of both resistors and FETs.
elib2cris::1512001600,heinrich2010
Keywords: Calibration; Resistors; Switches; Temperature dependence; Temperature distribution; Transistors; CMOS integrated circuits; CMOS voltage reference; PTAT current source; electronic calibration

Concept of an UHF Band Receiver for Spectrum Sensing Applications - Rieß, Steffen; Brendel, Johannes; Stöckle, Andreas; Rose, Richard; Fischer, Georg (IEEE International Symposium on Signals, Systems and Electronics, 2012)
Spectrum sensing is a major part for the implementation of Cognitive Radio (CR) systems in order to enable dynamic access to the radio frequency spectrum. This paper describes a concept for a scanning receiver in the UHF band from 470–870 MHz. Characteristics and design considerations of an Analog and Digital Front-End are given as well as the implementation of a Baseband Processor. This is the central module of the whole receiver and the interface to a higher-level controlling unit connected through a 100 Mbit/s Ethernet link. The control interface for the receiver is similar to a spectrum analyzer and therefore easy integrable in an already existing system. Special attention in the digital part is paid to an IF subsampling approach and the clock generation circuit for the ADC. For the sake of completeness the interface to a configurable antenna and some details to the realization of the power supply are also described. This concept has been implemented in hardware in order to enable investigations for the task of spectrum sensing. Our scanning receiver is part of a complex CR system for Professional Wireless Microphone Systems (PWMS) which should be able to provide a dynamic frequency allocation of the connected radio links.
elib2cris::1512001600,riess2012a

Concept on Frequency Agile Basestation System, Supporting Technologies and System Analysis - Fischer, Georg (Electrotechnical Colloquium, 2003)
elib2cris::1512001600,fischer2003a

Concepts and Components for Pulsed Angle Modulated Ultra Wideband Communication and Radar Systems - Eßwein, Alexander; Weigel, Robert; Carlowitz, Christian; Vossiek, Martin (Intech, 2013)
Ultra-Wideband Radio (UWB) earmarks a new radio access philosophy and exploits several GHz of bandwidth. It promises high data rate communication over short distances as well as innovative radar sensing and localization applications with unprecedented resolution. Fields of application may be found, among others, in industry, civil engineering, surveillance and exploration, for security and safety measures, and even for medicine. The book considers the basics and algorithms as well as hardware and application issues in the field of UWB radio technology for communications, localization and sensing based on the outcome of DFG's priority-funding program "Ultra-Wideband Radio Technologies for Communications, Localization and Sensor Applications (UKoLoS)".
elib2cris::1512001600,esswein2013
Keywords: Ultra Wideband

Concepts and Design Methods of Antennas for Automotive Long Range Radar Sensors - Wenig, Peter; Ußmüller, Thomas; Weigel, Robert (IEEE MTT-S International Microwave Symposium, Workshop on New Component Technologies for Vehicular and Industrial Radar Applications, 2009)
elib2cris::1512001600,wenig2009

Concepts for a Monostatic Radar Transceiver Front-end in eWLB Package with Off-Chip Quasi-Circulator for 60 GHz - Schmidbauer, Philipp; Wojnowski, Maciej; Weigel, Robert; Hagelauer, Amelie Marietta (2018 IEEE 20th Electronics Packaging Technology Conference (EPTC), 2018)

Concepts for Generation of Angle Modulated mm-Wave UWB Signals for Communication and Ranging - Carlowitz, Christian; Eßwein, Alexander; Weigel, Robert; Vossiek, Martin (IMS 2013 Workshop on RFICs/MMICs and Their Professional Wireless Sensing Applications, 2013)
UnivIS-Import:2015-04-16:Pub.2013.tech.IE.LEH.concep

Concepts for Ultra-Wideband Impulse-Radio Localization and Ranging - Hüttner, Jörg (Friedrich-Alexander-Universität Erlangen-Nürnberg, 2010)

Conceptual design of an automatized light control in a cowshed - Kilian, Jens; Werner, Daniel; Schneider, Michael; Schwenzfeier-Hellkamp, Eva (IEEE Power and Energy Student Summit 2016 (PESS 2016), 2016)

Conditional Capacity and Transmit Signal Design for SWIPT Systems with Multiple Nonlinear Energy Harvesting Receivers - Morsi, Rania; Jamali, Vahid; Hagelauer, Amelie Marietta; Ng, Derrick Wing Kwan; Schober, Robert (IEEE Transactions on Communications, 2020)
In this paper, we study information-theoretic limits for simultaneous wireless information and power transfer (SWIPT) systems employing practical nonlinear radio frequency (RF) energy harvesting (EH) receivers (Rxs). In particular, we consider a SWIPT system with one transmitter that broadcasts a common signal to an information decoding (ID) Rx and multiple EH Rxs. Owing to the nonlinearity of the EH Rxs' circuitry, the efficiency of wireless power transfer depends on the waveform of the transmitted signal. We aim to answer the following fundamental question: What is the optimal input distribution of the transmit signal waveform that maximizes the information transfer rate at the ID Rx conditioned on individual minimum required direct-current (DC) powers to be harvested at the EH Rxs? Specifically, we study the conditional capacity problem of a SWIPT system impaired by additive white Gaussian noise subject to average-power (AP) and peak-power (PP) constraints at the transmitter and nonlinear EH constraints at the EH Rxs. To this end, we develop a novel nonlinear EH model that captures the saturation of the harvested DC power by taking into account not only the forward current of the rectifying diode but also the reverse breakdown current. Then, we derive a novel semi-closed-form expression for the harvested DC power, which simplifies to closed form for low input RF powers. The derived analytical expressions are shown to closely match circuit simulation results. We solve the conditional capacity problem for real- and complex-valued signalling and prove that the optimal input distribution that maximizes the rate-energy (R-E) region is unique and discrete with a finite number of mass points. Furthermore, we show that, for the considered nonlinear EH model and a given AP constraint, the boundary of the R-E region saturates for high PP constraints due to the saturation of the harvested DC power for high input RF powers. In addition, we devise a suboptimal input distribution whose R-E tradeoff performance is close to optimal. All theoretical findings are verified by numerical evaluations.
CRIS-Team Scopus Importer:2020-02-04
Keywords: channel capacity; energy harvesting (EH); matched filters; nonlinear circuit analysis; rectennas; rectifiers; Schottky diodes; semiconductor detectors; signal design; Wireless power transmission

Consideration of higher frequency bands in accurate millimeter-wave FMCW-radar system simulations for automotive applications - Dudek, Manuel; Kissinger, Dietmar; Weigel, Robert; Fischer, Georg (Wireless and Microwave Technology Conference, 2011)
In this paper we demonstrate the necessity of taking harmonic bands into account when performing accurate simulations for millimeter-wave frequency-modulated continuous-wave (FMCW) radar systems. Especially under nonlinear conditions when harmonics are generated and influence the signal quality of target detection the higher frequency bands cannot be neglected anymore. In ordinary complex baseband simulations, that are considered as a means to keep the amount of data low in FMCW radar simulations, previous knowledge is needed to explicitly model the impact of effects in higher frequency bands on the specific circuit. Our approach takes the effects of multiples of the actual operating frequency into account, thus enabling higher accuracy while keeping the amount of data moderate. As an example for the capability of this simulation approach a scenario is calculated showing the difference between both simulation strategies.
elib2cris::1512001600,dudek2011a

Consideration of Nonlinear Effects in Different Receiver Architectures for Use in Passive Radar Systems - Horlbeck, Marie; Scheiner, Benedict; Weigel, Robert; Lurz, Fabian (2023 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications, PAWR 2023, 2023)
In passive radar systems the high dynamic range between the received reflected signal and the received signal of neighboring strong transmitters as well as the direct signal causes high demands on the receivers. Since a real receiver never shows a perfect linear characteristic, this always implies nonlinear effects. Consequently, the in the receiver generated interfering signals lead to a reduced total sensitivity. According to the intensity and spectral distribution of the input signals, intermodulation noise is produced. This paper shows a consideration and an estimation of nonlinear effects in different receiver architectures, depending on various measured input spectra for passive FM radar.
CRIS-Team Scopus Importer:2023-03-17
Keywords: intermodulation products; nonlinear effects; passive radar; receiver

Considerations for Capacitance Measurements of Antenna Tuning RF Switches on Board - Solomko, Valentyn; Özdamar, Oguzhan; Tayari, Danial; Voelkel, Matthias; Weiss, Simon; Essel, Jochen; Weigel, Robert; Hagelauer, Amelie (2021 IEEE INTERNATIONAL CONFERENCE ON MICROWAVES, ANTENNAS, COMMUNICATIONS AND ELECTRONIC SYSTEMS (COMCAS), 2021)
CRIS-Team WoS Importer:2022-09-30

Considerations for Harmonics Distribution in Aperture-Tuned Inverted-F Antenna for Cellular Handheld Devices - Özdamar, Oguzhan; Weigel, Robert; Hagelauer, Amelie; Solomko, Valentyn (IEEE Transactions on Microwave Theory and Techniques, 2020)
An analysis of the harmonics distribution in the aperture-tuned inverted-F antenna (IFA) using the first-order transmission line model is presented. The analysis allows identifying local minimums for the second and third harmonics for a given use case, providing the mechanism for optimization of the nonlinear performance of an antenna system. The theoretical findings are verified on a hardware demonstrator, comprising a mechanically reconfigurable IFA and a single-pole single-throw (SPST)-based aperture tuning network. The aperture tuning network comprises a radio frequency (RF) high-voltage switch, including a voltage detector with low-harmonic feedback and a parallel inductor. The integrated circuit (IC) was fabricated in Infineon 130-nm dedicated RF switch technology. The hardware demonstrator enables the measurements of the impedance at the feed, harmonics, RF voltage along the radiating element, and impedance at aperture tuning port. The latter provides a mechanism for optimization of load impedance at integer multiplies of transmitted frequencies, which allows minimization of harmonic content generated by the tuning IC.<br
Keywords: Antenna tuning; aperture tuning; carrier aggregation (CA; high-voltage radio frequency (RF) switch; inverted-F antenna (IFA); single-pole single-throw (SPST); voltage detector.

Considerations on Accurate Characterization of Differential Devices Using Baluns - Issakov, Vadim; Sene, Badou; Aguilar Mendoza, Erick; Werthof, Andreas; Jenei, Snezana; Weigel, Robert (European Microwave Conference, 2017)
Direct characterization of differential components requires multiport equipment, which is not always available. Thus, it is a common practice to attach balanced-unbalanced (balun) circuits to convert between single-ended and differential signals. However, removing impact of baluns from measured two-port S-parameters is a challenge, since baluns are threeport devices and classical de-embedding techniques are not applicable. Additionally, obtaining the S-parameters of baluns by two-port network analyzer is not trivial, since the ports at the differential side are tightly coupled. In this paper we address both challenges by proposing two techniques: how to characterize a balun using two-port measurements, and how to accurately de-embed the impact of balun characteristics from device-undertest (DUT) measurements. The applicability and accuracy of the proposed techniques is analyzed. For verification, the first technique has been applied to characterize an integrated ultrawideband (UWB) Marchand balun, and the second to de-embed the baluns impact from measured results of the balun-DUTbalun structure. The characterized DUT is a differential LNA operating in the range from 30 GHz to 110 GHz realized in 0.35 μm SiGe:C bipolar technology. The obtained de-embedded S-parameters are compared with the directly measured results<br
Keywords: S-Parameter; Balun; LNA

Considerations on Imedance Matrix Determination for Accurate Passive Device Chracterization - Weigel, Robert; Wojnowski, Maciej; Engl, Mario (IEEE Workshop on Signal Propagation on Interconnects, 2007)
For accurate RLCG-parameter extraction the measured S-parameter matrix needs to be converted to the Z-matrix. However, there exist three different definitions of S-parameters and consequently three different formulas of converting S-matrix into Z-matrix. In this article, we present an overview of existing S-parameters definitions and examine the uncertainties associated with the S-matrix to Z-matrix transformations. Further, we introduce an error estimator describing the inaccuracy one makes performing the incorrect transformation. We compare de-embedded measurement results of an inductor manufactured in Si-based MCM-D technology. We show that using wrong transformation can easily lead to erroneous or even catastrophic results.
elib2cris::1512001600,weigel2007a
Keywords: S-parameters; impedance matrix; network analysers; RLCG-parameter extraction; S-parameter matrix; Si-based MCM-D technology; Z-matrix; impedance matrix determination; passive device characterization; Calibration; Circuit simulation; Impedance measurement; Inductors; Matrix converters; Scattering parameters; Transmission line matrix methods; Transmission line measurements; Voltage; Waveguide theory

Contactless analysis of heart rate variability during cold pressor test using radar interferometry and bidirectional LSTM networks - Shi, Kilin; Steigleder, Tobias; Schellenberger, Sven; Michler, Fabian; Malessa, Anke; Lurz, Fabian; Rohleder, Nicolas; Ostgathe, Christoph; Weigel, Robert; Kölpin, Alexander (Scientific Reports, 2021)
Contactless measurement of heart rate variability (HRV), which reflects changes of the autonomic nervous system (ANS) and provides crucial information on the health status of a person, would provide great benefits for both patients and doctors during prevention and aftercare. However, gold standard devices to record the HRV, such as the electrocardiograph, have the common disadvantage that they need permanent skin contact with the patient. Being connected to a monitoring device by cable reduces the mobility, comfort, and compliance by patients. Here, we present a contactless approach using a 24 GHz Six-Port-based radar system and an LSTM network for radar heart sound segmentation. The best scores are obtained using a two-layer bidirectional LSTM architecture. To verify the performance of the proposed system not only in a static measurement scenario but also during a dynamic change of HRV parameters, a stimulation of the ANS through a cold pressor test is integrated in the study design. A total of 638 minutes of data is gathered from 25 test subjects and is analysed extensively. High F-scores of over 95% are achieved for heartbeat detection. HRV indices such as HF norm are extracted with relative errors around 5%. Our proposed approach is capable to perform contactless and convenient HRV monitoring and is therefore suitable for long-term recordings in clinical environments and home-care scenario
Keywords: hrv; radar; vitalparameter; herztöne; berührungslos; herzratenvariabilität

Contactless Carotid Pulse Measurement Using Continuous Wave Radar - Shi, Kilin; Schellenberger, Sven; Steigleder, Tobias; Michler, Fabian; Lurz, Fabian; Weigel, Robert; Kölpin, Alexander (2018 Asia-Pacific Microwave Conference, 2018)
Cardiovascular diseases are one of the major causes of death. Regular checkups and preventive actions can drastically help reducing fatal incidences. This can be achieved by monitoring the carotid artery or rather the carotid pulse signal. Commonly, ultrasound devices are used for that purpose. However, these devices are costly, mostly stationary and their usage requires training and experience. This paper investigates the possible usage of radar systems as a contactless and low-cost alternative for carotid pulse measurements. Theoretical investigations reveal a linear relationship between the measurands of both devices and synchronous recordings from three test persons further confirm the feasibility of using radar systems as a potential device for monitoring cardiovascular disease

Contactless Gas Mixture Measurements Using Distributed and Synchronized Low-Cost Millimeter-Wave FMCW Radar Sensors - Och, Andreas; Schrattenecker, Jochen O.; Schuster, Stefan; Holzl, Patrick A.; Freidl, Philipp F.; Weigel, Robert (2019 IEEE International Conference on Microwaves, Antennas, Communications and Electronic Systems, COMCAS 2019, 2019)
In a multitude of industrial processes, various sensing technologies are employed to monitor gaseous substances. However, many traditional sensor types are not suitable for operation under harsh environmental conditions. Radar-based time-of-flight permittivity measurements have been proposed as alternative but suffer from high cost and limited accuracy in highly cluttered industrial plants. We propose a novel concept that utilizes two synchronized low-cost frequency-modulated continuous-wave radar sensors for a direct transmission measurement with increased robustness and accuracy. A prototype based on fully-integrated millimeter-wave radar transceivers was realized and multiple measurements demonstrate a significant improvement to previously published techniques due to higher signal-to-noise ratio and compensation of systematic setup induced errors.
CRIS-Team Scopus Importer:2020-02-21
Keywords: gas detectors; millimeter wave radar; permittivity; phase estimation; radar measurements; time of arrival estimation

Contactless Person Identification Using Cardiac Radar Signals - Shi, Kilin; Will, Christoph; Weigel, Robert; Kölpin, Alexander (2018 IEEE International Instrumentation and Measurement Technology Conference (I2MTC), 2018)
Radar systems have been researched for the use of presence detection and contactless vital sign monitoring. However, there exists no established biometrics for remote and unique person identification during such monitoring. Conventional biometrics like fingerprint or iris scan yield the disadvantage that direct contact with the person is needed. This paper explores the possibility of using cardiac radar signals as new biometric parameter for unique person identification. Measurements on different persons are performed using a 24GHz continuous wave radar system which utilizes the Six-Port technology. An advanced signal processing and classification routine is presented to perform automatic person identification. Among several classifiers, quadratic support vector machines achieve the best performance and reach an overall accuracy of up to 94.6

Continuous EMC-Simulation in Automotive Applications - Stelzer, Andreas; Weigel, Robert (Progress in Electromagnetics Research Symposium, PIERS, 2003)
elib2cris::1512001600,stelzer2003a