M.Sc. Henning Poensgen

The increasing demand for high-data-rate wireless communication systems has driven research into the D-band frequency range (110–170 GHz). In phased array and beamforming systems, vector-modulated phase shifters are widely used to achieve precise phase and amplitude control for beam steering. These architectures rely on accurate amplitude weighting, typically implemented using a combination of variable gain amplifiers (VGAs) and attenuators, which generate the required vector modulation signals.

This bachelor thesis focuses on the schematic-level investigation and design of a variable gain amplifiers and attenuators operating at 140 GHz. The student will analyze suitable circuit topologies, evaluate their performance trade-offs between gain, linearity, bandwidth, stability and noise. A key challenge is maintaining low phase variation across all gain and attenuation states. 

Secondary goal is the investigation of various biasing techniques ( which maximize the usable resolution of a linear digital-to-analog converter) while maintaining complementary temperature variation to minimize temperature drift.

The analysis is carried out with a state-of-the-art 130nm BiCMOS process with advanced design tools such as Keysight ADS and Cadence Virtuoso.