An Efficient, High Power Q-Band SiGe HBT Power Amplifier With A Compact Four-Way Wilkinson Power Combiner Balun for Emerging Very Low-Earth-Orbit SATCOM

This work presents an energy-efficient, high power Q-band SiGe HBT cascode power amplifier (PA). A novel four-way Wilkinson power combiner balun (WPCB), realized by two coupled line impedance inverting baluns, is proposed not only to simplify signal routing for compact size, but also to obtain efficient power combining with an excellent signal balance. A prototype Q-band PA attains measured peak P
out
, peak PAE, and power gain of 24.0 dBm, 35.3%, and 23.0 dB at 43.0 GHz, respectively, the highest power density among any Q-band Sibased PAs. Its 1 dB P
out
bandwidth (BW) ranges from 37.0 to 43.0 GHz, covering downlink of Very Low Earth orbit (VLEO) satellite communication (SATCOM). The PA delivers P
avg
of 18.1 dBm with PAE
avg
of 21.0% at 250MHz symbol rate DVB-S2X 64 APSK modulation.