Digital microwave power amplifiers for energy-efficient and wireless sub-THz communication

• Applicants: Professor Dr.-Ing. Matthias Rudolph; Dr.-Ing. Andreas Wentzel
• Subject Area: Electronic Semiconductors, Components and Circuits, Integrated Systems, Sensor Technology, Theoretical Electrical Engineering
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 404909432

In the course of the newest developments in mobile communications (e.g. 5G and IoT) much higher data rates and throughput need to be ensured. Thus, due to its much higher bandwidth (10x), the sub-THz frequency region is targeted more and more. This drives the need for energy-efficient RF microwave power amplifiers (RF PA) at sub-THz (100 GHz+). As the RF PA is the most power hungry part in a base station they represent an important part when focusing Green-IT. In the proposed project, for the first time hybrid amplifier modules for the W- and G-band will be realized, which follow the digital approach. In addition, the focus of both RF PA modules is on minimizing the efficiency drop above the (reduced) signal input power. This is necessary in applications with high signal bandwidths because the amplifiers must work well below the maximum input power range for most of the time. With this project, the basis for the further development of the 5G standard is already being generated with novel amplifier architectures that can potentially deliver comparatively high efficiencies with very broadband input signals and are also compact and flexible. In particular, the use of frequency multiplier drivers allows a sinusoidal input signal that is compatible with conventional generators. With the digital PA approach, the goals in technology (here: InP DHBT transfer substrate) and modeling are closely linked:In addition to the implementation of digital amplifier MMICs (including driver and filter) for the W-band (100 GHz) with a total efficiency of over 50% and a maximum output power of at least 100 mW, the proposed concept is shown at G-band (200 GHz) as well. Important insights regarding the evaluation of the digital circuit concept in the sub-THz range are expected. In addition, the question should be answered as to whether the existing InP technology is suitable for the proposed circuit concept. In transistor modeling, aperiodically switched power transistors are modeled for the linear amplification of broadband digitally modulated signals at highest frequencies. For this purpose, the periphery (supply line, contacts) of the HBT is described and optimized up to the highest frequencies. The influence and the optimization of the connections on the switching behavior are clarified. At the same time, the question of the meaningful definition of reference levels is examined. Another goal in modeling is the numerically robust, efficient and accurate model for switching operation. For this, the type of characterization and any reductions in the measurement effort for modeling are examined.

• DFG Programme: Research Grants