The evolution of transistors for power amplifiers: 1947 to today

This paper traces the development of transistors for power amplifiers (PAs). Technological transistor innovations have raised output power levels, the frequency of operation and the efficiency of power amplifiers. Devices to be discussed include the bipolar junction transistor (BJT), heterojunction bipolar transistor (HBT), complimentary metal oxide semiconductor (CMOS), laterally diffused metal oxide semiconductor (LDMOS), metal-semiconductor field effect transistor (MESFET), high electron mobility transistor (HEMT), and pseudomorphic high electron transistor (PHEMT). Semiconductors for PAs include Silicon (Si), Gallium Arsenide (GaAs), Indium Phosphide (InP), and Gallium Nitride (GaN) and the various heterojunctions of these semiconductors.