RF/microwave transistors: evolution, current status, and future trend

Most applications for radio frequency/microwave (hereafter called RF) transistors had been military oriented in the early 1980s. Recently, this has changed drastically due to the explosive growth of the markets for civil wireless communication systems. This paper gives an overview on the evolution, current status, and future trend of transistors used in RF electronic systems. Important background, development and major milestones leading to modem RF transistors are presented. The concept of heterostructure, a feature frequently used in RF transistors, is discussed. The different transistor types and their figures of merit are then addressed. Finally an outlook for expected future developments and applications of RF transistors is given.