Significant investments and R&D efforts over the past two decades have esta
blished GaAs and InP electronic device technologies from substrate manufact
uring to MMIC amplifier design and testing. Today, GaAs and InP HBTs and HF
ETs, as far as gain, efficiency, and power are concerned, dominate the whol
e spectrum from S- to W-band and beyond, In this paper we will discuss rece
nt advances in device technologies and survey the state of the art performa
nce of GaAs and InP HFETs and HBTs.