Microwave FET's - What's next

The paper presents some of the recent advances in low-noise GaAs FET's and efficient power amplification. Further advancements are predicted that will lead to (1) shorter (approximately 0.2 microns) gate lengths, (2) graded doping profiles in the channel, (3) heterojunction carrier confinement at the channel-substrate interface and (4) monolithic tuning on the chip using plated, air-suspended lumped inductors. High mobility at the interface between the active layer and the substrate as well as short channel length and low ohmic-contact resistance are found to be some of the key parameters enabling low noise behavior.