Robert Weigel

Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Bavaria, Germany

Are you Robert Weigel?

Claim your profile

Publications (810)202.32 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In recent years, the ultra-high frequency (UHF) band from 470-862 MHz has been subject to several changes in frequency allocation, and a final decision for new services is still under discussion. Until 2010, this band was exclusively assigned to stations for terrestrial digital video broadcasting (DVB-T) [1]. The current demand for ever increasing data rates for mobile devices has led to changes in frequency range assignments. The key term "digital dividend" is frequently used by regulatory bodies and well-known in the cognitive radio community. In its first rollout, the band from 790-862 MHz was brought up for auction to mobile network operators in Germany [2]. The total revenue for 60 MHz of spectrum was ?3,575 billion [2], [3], which underlines the great market value of the radio spectrum.
    No preview · Article · Jan 2016 · IEEE Microwave Magazine
  • [Show abstract] [Hide abstract]
    ABSTRACT: The modeling of bulk acoustic wave resonators at elevated power levels has been improved by taking the spatial distribution of the dominating loss mechanisms into account. The spatial distribution of the dissipated power enables more accurate modeling of the temperature increase caused by the applied power. Thus, it is also possible to more accurately model the frequency shifts of the resonators' impedance curves resulting from the temperature increase caused by the applied power. Simulation and measurement results for the temperatures and impedances of the resonators with different layerstacks at high power loads are presented. The simulation and measurement results are in good agreement, confirming the presented modeling approach. Furthermore, the de-embedding procedure used to obtain vectorial scattering parameters of the resonators during high power loads, the according measurement setup, and the procedure for measuring absolute temperatures by infrared thermography are discussed.
    No preview · Article · Oct 2015 · IEEE transactions on ultrasonics, ferroelectrics, and frequency control
  • Ahmed Gharib · Robert Weigel · Dietmar Kissinger
    [Show abstract] [Hide abstract]
    ABSTRACT: 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.
    No preview · Article · Oct 2015 · IEEE Transactions on Microwave Theory and Techniques
  • F. Trenz · V.Kalpen · R. Weigel · D. Kissinger
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a blood-equivalent liquid is presented. The phantom material at room temperature is a valid representation of blood at body temperature in the frequency range from 2 to 3 GHz with an maximum deviation of +-1.5 in epsilon' and +-2.8 in epsilon ''. The effect of a hypertonic variation of the plasma hydration level has been modeled by varying the amount of water +-14% in the tissue-equivalent fluid. Transmission based measurements have been performed on a tube phantom of PMMA with narrowband patch antennas on flexible substrates. The antennas have been placed at opposite sides of the phantom and measurements have been performed at different hydration levels of the substitute liquid. A clear distinction of the levels can be seen in both magnitude and phase of the transmission coefficient.
    No preview · Conference Paper · Sep 2015
  • F. Trenz · M. Hofmann · R. Weigel · D.Kissinger
    [Show abstract] [Hide abstract]
    ABSTRACT: In this paper, a planar broadband sixport reflectometer structure is presented. A frequency range from 3 to 29 GHz could be achieved by merging broadband components into a single multilayer PCB stackup with an area of 66x55 mm2. The reflectometer architecture used herein allows a frequency independent q-point configuration of the sixport by implementing microstrip linelength compensation. Broadband matching of around -10dB has been achieved at all ports in a frequency range from 1 to 30\,GHz. Furthermore, sufficient coupling from DUT port to measurement output could be reached in a range from 2 to 29GHz. Frequency compensation of the structure and an optimal q-point constellation of 120-120-120 have been verified by measurement. Due to its broadband functionality, compactness and cost efficiency, the proposed system is suitable for a wide range of microwave measurement applications.
    No preview · Conference Paper · Sep 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents our recent work towards state-of-the-art integrated test concepts for the in-situ characterization of silicon-integrated millimeter-wave devices and transceiver components for radar and communication applications. Narrowband as well as ultra-broadband integrated network analysis solutions for a variety of frequency bands ranging from 50 to 120 GHz are outlined. In this context, direct-conversion and heterodyne architectures and their respective implementations in silicon-germanium technologies are discussed.
    No preview · Article · Aug 2015
  • Source
    Roland Weiss · Fei Xie · Robert Weigel
    [Show abstract] [Hide abstract]
    ABSTRACT: Nowadays, dc current is much more widely used than a decade ago, not only in the well-known high-voltage dc transmission but also as dc-powered marine systems, dc data centers, and dc fast charging systems for electric vehicles. However, galvanically isolated dc voltage or current sensors are, in terms of accuracy, noise level, or dimensions, still far behind the ac measurement devices in low and medium voltage areas. In this paper, a giant-magnetoresistive-based sensor system for galvanic isolated dc current and
    Full-text · Article · Aug 2015 · IEEE Transactions on Instrumentation and Measurement
  • [Show abstract] [Hide abstract]
    ABSTRACT: For the first time the Polyharmonic Distortion (PHD) model has been used to characterize the nonlinearities of Bulk Acoustic Wave (BAW) components. For that purpose a measurement setup has been developed by extending a nonlinear vector network analyzer with required external components enabling X-parameter measurements at high power levels. By discussion of selected components of the BAW resonator's PHD model and performing simulations in an RF design environment the importance of PHD model for improved BAW filter design has been demonstrated.
    No preview · Article · Jul 2015
  • Source
    Fei Xie · Roland Weiss · Robert Weigel
    [Show abstract] [Hide abstract]
    ABSTRACT: Nowadays, dc current is much more widely used than a decade ago, not only in the well-known high-voltage dc transmission but also as dc-powered marine systems, dc data centers, and dc fast charging systems for electric vehicles. However, galvanically isolated dc voltage or current sensors are, in terms of accuracy, noise level, or dimensions, still far behind the ac measurement devices in low and medium voltage areas. In this paper, a giant-magnetoresistive-based sensor system for galvanic isolated dc current and voltage measurements is introduced. The system mainly consists of a special coil arrangement with low inductance for voltage measurement, a special U-turn for current measurement, and A/D converters with a low-cost field-programmable gate array for signal conditioning. The sensor system showed an outstanding measurement accuracy of 0.3% for voltage values up to ±550 V and 0.2% for current values up to ±100 A in a temperature range from -30 °C to 90 °C. This completely new approach for the galvanically isolated measurement of electric voltage and current avoids the use of bulky magnetic components and expensive power-consuming analog electronics, which allows one to integrate it in the current ac measure unit for power monitoring.
    Full-text · Article · Jul 2015 · IEEE Transactions on Instrumentation and Measurement
  • J. Nehring · M. Bartels · R. Weigel · D. Kissinger
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper proposes a permittivity sensitive phase-locked loop (PLL) for the characterization of biologically and medically relevant materials and liquids in a frequency frange from 19.2 GHz to 20.8 GHz. It utilizes a custom design voltage controlled oscillator (VCO) with a tank-integrated capacitive sensor fabricated on a SiGe process. A change of the permittivity opposed to the sensor leads to a frequency shift which will be regulated by the PLL. Thus, the permittivity of a MUT is directly mapped to the resulting DC tuning voltage generated by the control loop. The sensor is configured and read-out by a microcontroller. The system is used to characterize solutions of ethanol-methanol mixtures with concentration differences of 5 percent around a mixture ratio of 50:50.
    No preview · Article · Jul 2015
  • Source
    Fei Xie · Roland Weiss · Robert Weigel
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a novel hysteresis compensation method for increasing the measurement accuracy of magnetoresistive (MR) sensors such as AMR (anisotropic magnetoresistance), GMR (giant magnetoresistance) and TMR (tunnel magnetoresistance) sensors. A coil consisting of one winding is processed on top of the sensor element. This configuration allows short current pulses (positive and negative) to generate a defined magnet field, which should be much stronger than the field to be measured. In this case the MR sensors can always be kept in the same magnetic loop (major loop) during the measurement cycle. By demodulating or averaging the output signal of the sensor, the influence of the sensors hysteresis can be largely reduced. A mixed signal circuit consisting of a FPGA, analog to digital converters and analog switches is used to generate the pulses. AMR, GMR and TMR current sensors are chosen as examples in the experiment. Current measurements with and without controlled magnetic field pulse are compared. A hysteresis reduction to nearly 20% of the original value, by using the novel hysteresis compensation method, is reached.
    Full-text · Article · Jun 2015 · IEEE Transactions on Industrial Electronics
  • Source
    Fei Xie · Roland Weiss · Robert Weigel
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a novel hysteresis compensation method for increasing the measurement accuracy of magnetoresistive (MR) sensors such as AMR (anisotropic magnetoresistance), GMR (giant magnetoresistance) and TMR (tunnel magnetoresistance) sensors. A coil consisting of one winding is processed on top of the sensor element. This configuration allows short current pulses (positive and negative) to generate a defined magnet field, which should be much stronger than the field to be measured. In this case the MR sensors can always be kept in the same magnetic loop (major loop) during the measurement cycle. By demodulating or averaging the output signal of the sensor, the influence of the sensors hysteresis can be largely reduced. A mixed signal circuit consisting of a FPGA, analog to digital converters and analog switches is used to generate the pulses. AMR, GMR and TMR current sensors are chosen as examples in the experiment. Current measurements with and without controlled magnetic field pulse are compared. A hysteresis reduction to nearly 20% of the original value, by using the novel hysteresis compensation method, is reached.
    Full-text · Article · Jun 2015 · IEEE Transactions on Industrial Electronics
  • F. Lurz · S. Mann · S. Linz · S. Lindner · F. Barbon · R. Weigel · A. Koelpin
    [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents a low power 24GHz Doppler radar system for presence detection and occupancy monitoring. It is based on a minimalistic hardware approach and is able to wirelessly sense human respiratory signals so that even non-moving persons can be detected. By intermittently measuring, the average power consumption could be significantly reduced down to e.g. 0.2mW for 20 measurements per second. Experiments verify that, due to the short wavelength, the single channel receiver limitations can be neglected when only a detection of human respiratory but no evaluation of the breathing frequency is necessary.
    No preview · Article · Jun 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Radar sensors play a key role in today's industrial automation. Besides high accuracy, modern radar sensors have to feature high precision as well as challenging update rates. Six-Port wave correlators enable high phase resolution at high frequencies and therefore a high accuracy in radar applications. A low-cost Schottky diode detector applied to a substrate integrated waveguide (SIW) Six-Port is presented and measured. Furthermore, a displacement measurement using the SIW structure is performed.
    No preview · Article · Jun 2015
  • M. Sporer · F. Lurz · E. Schluecker · R. Weigel · A. Koelpin
    [Show abstract] [Hide abstract]
    ABSTRACT: With the growing application of autonomous underwater vehicles (AUV) and underwater construction, i.e. robotic manipulator and maintenance systems, there is an increasing demand on precise underwater distance sensors. In this paper we present a low-cost, short-range and contactless sensor which uses electromagnetical (EM) waves for measuring distances underwater. The measurement system is based on interferometric radar applying a six-port interferometer and using EM waves at a frequency of 2.4 GHz. Measurement series in fresh water have been carried out showing an precision of below 100μm up to a distance of 35mm with only 8dBm of transmit power. Due to the high measurement rate the system can also be employed for vibration analysis. Additionally, by connecting a commercial 2.4 GHz data transceiver, it is imaginable for the system to be simultaneously used for high data rate communication between, e.g. AUV and unmanned underwater platforms (UUP).
    No preview · Article · Jun 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: This paper presents an overview of wireless integrated sensor node realizations for indoor monitoring and localization applications. Depending on the targeted application scenario different wireless sensor node implementations based on either high-performance processors or semi-passive radio-frequency identification (RFID) cores are outlined. The presented high-performance node realization with monitoring and seamless indoor and outdoor localization capability can operate independently for a duration of one day and additionally features wireless charging. Furthermore, a UHF RFID Gen2 sensor tag for indoor localization and fall detection is presented that enables a battery lifetime of approximately one month. Finally, ultra-low-power UHF RFID sensor node concepts based on sub-threshold wake-up receivers are introduced that can achieve operational times of several years for specific low duty cycle scenarios.
    No preview · Article · Jun 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: Due to the growing market for Micro Electro Mechanical Systems (MEMS), especially for the application in mobile electronic devices like cameras, phones or tablet computers, cost and time efficient test and evaluation systems are required for the production process. This work presents a novel measurement setup for MEMS microphones, that allows an inline, contactless evaluation of the microphones' mechanical sensitivity at an early stage of the manufacturing process. A heterodyne receiver with a Six-port demodulator is deployed for displacement detection with micrometer resolution. Since the Six-port demodulator allows very high sampling rates, only limited by the analog-to-digital converter, short measurement times can be achieved.
    No preview · Conference Paper · Jun 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: This publication will show some considerations for selecting an appropriate analog-digital-converter (ADC) in Six-Port based radar systems for distance measurements. It will be discussed how the ADC resolution is limiting the overall system range resolution. Furthermore, configurations with non-synchronous sampling of the four baseband signals and their influences on the system performance will be investigated.
    No preview · Conference Paper · Jun 2015
  • [Show abstract] [Hide abstract]
    ABSTRACT: A new semi-physical memoryless computationally effective behavioral model (BM) capable of predicting amplitude-modulation-to-amplitude-modulation (AM–AM) and amplitude-modulation-to-phase-modulation (AM–PM) distortions is proposed. In recent years, AM–AM and AM–PM distortions have been separately studied in literature. Here, we investigate the correlation between AM–AM and AM–PM distortions first. Based on the observed correlation, a novel AM–PM model is derived from the well-known Rapp AM–AM model. On the basis of the close relationship between the AM–AM and AM–PM model, a highly accurate and computationally effective large-signal BM is obtained. The newly developed model addresses the current needs of the mobile industry that requires BMs of the power amplifier (PA), which can be interpreted by the designers. In addition, the models must be computationally effective due to the limited computation power in mobile handset. Therefore, only memoryless BMs can be taken into account and larger errors are accepted for the sake of computational effectiveness. In this paper, it is shown that the newly introduced model achieves excellent results, when it is applied to actual industrial applications of two GaAs-based class-AB PAs in 65-nm technology and one CMOS-based class AB PA in 28-nm technology, which are designed for mobile communications.
    No preview · Article · Jun 2015 · IEEE Transactions on Microwave Theory and Techniques
  • [Show abstract] [Hide abstract]
    ABSTRACT: The increase of leakage current in deep-submicrometer MOS transistors operated below threshold is becoming a reliability concern for scaled technology nodes. Especially high-power analog applications like high efficiency PAs and RF-switches undergo to strong lateral field when Vg <Vth. Indeed an increased degradation for these MOS applications was already reported in the state of the art but not completely understood. In this paper a thorough study of the DC non-conducting (NC) stress is presented and a new physical model describing the worsening of the electrical parameter is proposed. This model is suitable for being extended to the high frequency regime by means of a quasi-static sum (QS). For the first time RF stress measurements are conducted in various NC configurations. No frequency dependency is detected up to 4Ghz and the QS model is able to precisely predict the performance degradation.
    No preview · Article · May 2015

Publication Stats

4k Citations
202.32 Total Impact Points

Institutions

  • 2003-2015
    • Friedrich-Alexander-University of Erlangen-Nürnberg
      • • Department of Computer Science
      • • Lehrstuhl für Technische Elektronik
      Erlangen, Bavaria, Germany
    • Universitätsklinikum Erlangen
      Erlangen, Bavaria, Germany
  • 2006-2013
    • Nuremberg University of Music
      Nuremberg, Bavaria, Germany
    • IST Austria
      Klosterneuberg, Lower Austria, Austria
  • 2009
    • Technische Universität Dresden
      Dresden, Saxony, Germany
  • 2000-2008
    • Infineon Technologies
      München, Bavaria, Germany
    • Technische Universität Clausthal
      • Department of Electrical Information Technology
      Bergstadt-Clausthal-Zellerfeld, Lower Saxony, Germany
  • 2007
    • Fraunhofer Institute for Algorithms and Scientific Computing SCAI
      Sankt Augustin, North Rhine-Westphalia, Germany
  • 2003-2007
    • Linz Center of Mechatronics GmbH
      Linz, Upper Austria, Austria
  • 1997-2004
    • Johannes Kepler University Linz
      • Institut für Nachrichtentechnik und Hochfrequenzsysteme
      Linz, Upper Austria, Austria
  • 2000-2001
    • Chiba University
      • • Faculty of Engineering
      • • Department of Electrical and Electronic Engineering
      Chiba-shi, Chiba-ken, Japan
  • 1988-1999
    • Siemens
      München, Bavaria, Germany
  • 1997-1998
    • Vienna University of Technology
      • Institute of Sensor and Actuator Systems
      Wien, Vienna, Austria
  • 1991-1994
    • Technische Universität München
      • Department of High Frequency Engineering
      München, Bavaria, Germany