Digital microwave power amplifiers for energy-efficient and wireless sub-THz communication
Final Report Abstract
In the course of developments in broadband mobile communication (e.g. 5G with the Internet of Things (IoT)), much higher data volumes and rates must inevitably be guaranteed. The sub-THz frequency ranges (from 100 GHz) are also increasingly coming into focus here, as up to 10 times more bandwidth is available there compared to the conventional mobile communications range. This is the driving force behind energy-efficient RF power amplifiers in this frequency range. As these account for the majority of a base station’s total energy consumption, they are an important factor for green IT. In this project, hybrid amplifier modules for the W- and G-band were to be realized for the first time, following the digital approach. In addition, the question was to be answered as to whether the existing InP technology is suitable for the proposed circuit concept. An analysis carried out at the beginning of the project showed that the available technology does not allow purely digital circuit concepts at 100 GHz and beyond due to the still too low cut-off frequencies. Transistors with higher cutoff frequencies were not available, which was not foreseeable at the time of the project application. For this reason, switched amplifiers were not yet realized purely digitally, but as a class E type at 100 GHz and integrated into a module. The circuit design was supported by modeling the InP DHBTs used. First of all, the validity range of the model was significantly increased in frequency by analyzing the parasitic capacitances using electromagnetic simulation. For a better simulation of the switching behavior, a new phyiscally based model of the saturation region was implemented in the existing FBH-HBT model. Finally, the loss mechanisms that occur in the switching behavior were modeled using an analytical approximation in order to understand the existing limitations in terms of efficiency. Although the achieved performance parameters of approx. 10 dBm output power and around 25% PAE at 100 GHz are well below the project target, the values stand up well to comparison with the state of the art. The knowledge gained with regard to the loss mechanisms and the improvements in transistor modeling will be incorporated into the further development of the InP DHBT technology.
Publications
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“An Improved EM-Simulation Procedure to Extract Extrinsic Elements of Terahertz InP DHBTs,” in 2020 German Microwave Conference (GeMiC), Mar. 2020, pp. 240–243.
S. V. Pawan, T. K. Johansen, K. Erkelenz, A. Wentzel, R. Doerner, S. Boppel & M. Rudolph
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“Output Matching Network Design for Highly Efficient InP-DHBT W-Band PAs Utilizing a Defected Ground Structure, “ in Proceedings of German Microwave Conference 2020, Cottbus, Germany.
K. Erkelenz, P. Sriperumbuduri, T. Flisgen, M. Rudolph, T. K. Johansen, W. Heinrich & A. Wentzel
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Modeling Base-Collector Heterojunction Barrier Effect in InP DHBTs for Improved Large Signal Performance. 2021 IEEE MTT-S International Microwave Symposium (IMS), 355-357. IEEE.
Sriperumbuduri, Venkata Pawan; Yacoub, Hady; Johansen, Tom K.; Wentzel, Andreas; Doerner, Ralf & Rudolph, Matthias
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A 100 GHz Class-F-Like InP-DHBT PA with 25.4% PAE. 2021 16th European Microwave Integrated Circuits Conference (EuMIC), 225-228. IEEE.
Shrestha, Amit; Doerner, Ralf; Yacoub, Hady; Johansen, Tom K.; Heinrich, Wolfgang; Krozer, Viktor; Rudolph, Matthias & Wentzel, Andreas
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Mathematical Analysis of Switching HBT Devices. 2022 IEEE Microwaves, Antennas, and Propagation Conference (MAPCON), 827-831. IEEE.
Sriperumbuduri, Venkata Pawan; Wentzel, Andreas & Rudolph, Matthias
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Design and Analysis of a 50GHz InP DHBT Class-E Power Amplifier Providing 2.3 mW/µm2. 2023 18th European Microwave Integrated Circuits Conference (EuMIC), 285-288. IEEE.
Sriperumbuduri, Venkata Pawan; Yacoub, Hady; Wentzel, Andreas; Johansen, Tom K. & Rudolph, Matthias
