AlGaAs/InGaAs heterostructures with doped channels for discrete devices and monolithic amplifiers

AlGaAs/InGaAs/GaAs-type heterostructure with one or two doped channels have been used to fabricate both discrete devices and monolithic amplifiers for millimeter-wave operation. Maximum current densities of 1 A/mm and maximum transconductances of 530 mS/mm were obtained. 0.25*50 mu m discrete devices delivered a power density of 1 W/mm with 2.9-dB gain and 25% efficiency at 60 GHz. A 100- mu m monolithic one-stage amplifier demonstrated 93 mW (0.93-W/mm power density) at 31.5 GHz with 4.2-dB gain and 29% efficiency. A record 34% efficiency was achieved with a 53.7-mW output power and 4.8-dB gain.>