44 GHz hybrid HEMT power amplifiers

Doped-channel, 0.25- mu m-gate-length, InGaAs pseudomorphic HEMTs (high electron mobility transistors) have been developed which exhibit state-of-the-art power performance at millimeter-wave frequencies, with output power density of 0.93 W/mm and power-added efficiency of 41% at 44 GHz. Using these devices, two Q-band hybrid power amplifiers have been developed. A two-stage design has produced 108 mW output power gain with 9.5 dB and 26.5% power-added efficiency. A three-stage design produced 251 mW output power with 13.6 dB of gain and 26.8% power-added efficiency. The peak efficiency of the three-state amplifier was 31.3% when biased differently. The linear gain of these amplifiers was 12 and 20 dB respectively. It is concluded that these amplifiers are an attractive alternative for designers of future millimeter-wave transmitters.<>