@misc{ManchandaKnaackLiaoetal., author = {Manchanda, Prabhav and Knaack, Marcus and Liao, Juhua and Andrei, Cristina and Rudolph, Matthias}, title = {Detection of vital signs using noncoherent receivers}, series = {2025 22nd European Radar Conference (EuRAD)}, journal = {2025 22nd European Radar Conference (EuRAD)}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-2-87487-083-5}, doi = {10.23919/EuRAD65285.2025.11233845}, pages = {363 -- 366}, abstract = {This work introduces a novel concept for detecting displacements, specifically vital signs resulting from physiological activity, using noncoherent receivers. A theoretical analysis of phase noise propagation in the receiver architecture reveals that individual uncorrelated phase noise contributions add at the intermediate frequency, thereby defining the detection sensitivity. System validation using a reflector mounted on a modulator producing controlled oscillations demonstrates the ability to detect sub-millimeter displacements, provided the residual phase noise from the uncorrelated oscillators remains low. Extending this concept, the system accurately detects respiration and cardiac activity, with results is comparable to those of a reference ECG sensor. These findings open new possibilities for multistatic vital sign detection systems, offering reliable, non-contact sensing for healthcare and remote monitoring applications.}, language = {en} } @misc{KrishnajiRaoWentzelHoffmannetal., author = {Krishnaji Rao, Megha and Wentzel, Andreas and Hoffmann, Thomas and Schellhase, Lars and A. Chevtchenko, Serguei and Yazdani, Hossein and Rudolph, Matthias}, title = {Digital GaN-based transceiver architectures for sustainable 5G networks}, series = {International journal of microwave and wireless technologies}, journal = {International journal of microwave and wireless technologies}, publisher = {Cambridge University Press (CUP)}, address = {Cambridge}, issn = {1759-0787}, doi = {10.1017/S1759078725102262}, pages = {1 -- 9}, abstract = {This paper presents two distinct configurations of a GaN-based digital transceiver (TRx) to evaluate their performance and integration efficiency. The first configuration, features a novel low-noise amplifier with integrated switching capability (LNAiS) and a digital class-E power amplifier (PA) on a single compact chip. The LNAiS eliminates the need for an external antenna switch, reducing module complexity and chip size while maintaining high performance. It achieves a gain of 12.7 dB and a noise figure of 3 dB at 4.7 GHz in Rx mode and provides over 20 dB isolation in Tx mode across 4.7-7.4 GHz. The digital PA demonstrates flexibility and efficiency, achieving 46\% and 23\% efficiencies for 20 MHz LTE and OFDM signals, respectively, and 22\% for a 240 MHz OFDM signal with 10 dB PAPR. The second configuration integrates the same concept of digital PA with a standard LNA and an SPDT switch (LNAsS), achieving a gain of 24.8 dB and a noise figure of 2.65 dB at 4.2 GHz. This work highlights the trade-offs between these two architectures and demonstrates that the LNAiS-based approach drives the development of greener, more flexible, compact,lower-complexity, and cost-effective transceivers for 5G networks.}, language = {en} } @misc{BeleniotisZervosKrauseetal., author = {Beleniotis, Petros and Zervos, Christos and Krause, Sascha and Yazdani, Hossein and Rudolph, Matthias}, title = {Traps in GaN HEMTs : from characterization to model development and device optimization}, series = {2025 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS)}, journal = {2025 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS)}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {979-8-3315-9172-4}, doi = {10.1109/BCICTS63111.2025.11211504}, pages = {1 -- 8}, abstract = {This paper reviews a comprehensive strategy designed to address the impact of traps across the entire field of GaN HEMT operation. It begins with the characterization of trap levels and the measurement of trap time constants. The study then progresses to TCAD simulations to examine the location of the observed trap levels and their effect on device performance. Finally, it introduces the development of a compact trap model grounded in Shockley-Read-Hall statistics. The proposed model is capable of accurately predicting trapping effects across all combinations of voltage, temperature, and time. The paper concludes by highlighting the synergy TCAD-compact-model, underscoring its utility in device optimization schemes.}, language = {en} } @misc{RaoBeleniotisHoffmannetal., author = {Rao, Megha Krishnaji and Beleniotis, Petros and Hoffmann, Thomas and Yazdani, Hossein and Wentzel, Andreas and Rudolph, Matthias}, title = {Switch-integrated GaN LNAs : a technology-focused analysis}, series = {2025 20th European Microwave Integrated Circuits Conference (EuMIC)}, journal = {2025 20th European Microwave Integrated Circuits Conference (EuMIC)}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-2-87487-082-8}, doi = {10.23919/EuMIC65284.2025.11234676}, pages = {29 -- 32}, abstract = {This paper presents the first circuit-level analysis of a two-stage GaN-HEMT LNA with an integrated switch, comparing two distinct technologies: one with a standard passivation layer (Type A) and another featuring an advanced passivation layer (Type B). Through a detailed evaluation of their performance in both amplification and isolation modes, the study highlights Type B as a significant advancement over Type A. Leveraging technological enhancements, including an improved passivation layer and slightly optimized component matching, Type B demonstrates superior performance. The results are compelling, with Type B achieving a gain of 19 dB, a low noise figure of 1.17dB, and small-signal isolation exceeding 30 dBm at 5.2 GHz. These achievements establish Type B as a formidable option for future 5G telecommunication systems, offering a performance that challenges traditional designs that use separate switches.}, language = {en} } @misc{OkochaAndreiRudolph, author = {Okocha, Jonathan and Andrei, Cristina and Rudolph, Matthias}, title = {On the repeatability of low cost varactor—based RF impedance tuners}, series = {2025 55th European Microwave Conference (EuMC)}, journal = {2025 55th European Microwave Conference (EuMC)}, publisher = {IEEE}, address = {Piscataway, NJ}, isbn = {978-2-87487-081-1}, doi = {10.23919/EuMC65286.2025.11234977}, pages = {683 -- 686}, abstract = {This paper introduces a concise methodology for assessing the repeatability of low-cost, varactor-based RF impedance tuners by employing a dB-based metric that quantifies how accurately each tuner reproduces a target impedance over repeated cycles. Both blocked and cyclical measurement strategies are used to highlight large impedance transitions near high-reflection states that exacerbate non-idealities. In addition, the method rigorously characterizes issues such as systematic offsets, drift, and hysteresis, common challenges that can impair tuner performance, allowing targeted improvements. Demonstrations with a BST varactor prototype underscore the importance of identifying and quantifying these effects to ensure consistent tuner performance in real-world RF testing environments.}, language = {en} } @incollection{GailingNaumannRudolph, author = {Gailing, Ludger and Naumann, Matthias and Rudolph, David}, title = {Local and regional conflicts in the energy transition}, series = {Reference module in materials science and materials engineering}, booktitle = {Reference module in materials science and materials engineering}, publisher = {Elsevier BV}, address = {Amsterdam}, isbn = {978-0-12-803581-8}, doi = {10.1016/B978-0-443-29210-1.00073-X}, pages = {1 -- 9}, abstract = {Energy transitions are accompanied by a range of conflicts, which mostly occur at local and regional scales. To help understand these, this chapter provides a typology of energy conflicts, of which the most common are distribution and procedural conflicts. Energy conflicts entail material, spatial, temporal and actor dimensions. For both major types of energy conflict and their different dimensions, the chapter provides empirical examples from Denmark and the United Kingdom. Energy conflicts are a challenge for energy transitions, but they are also drivers of social change, which are inherent in the pluralistic structure of modern societies.}, language = {en} }