Therwally-stable AlGaAs/GaAs microwave power HSTs

Abstract

The main advantage of HBT as a power device at microwave frequencies stems from its high power density. The electronic limitation of modern HBTs with heavily doped base layers can be as high as 8-10 x 105 W/cm2(or 8-10 mW/pm2) of emitter area. Higher emitter injection efficiency afforded by low base sheet resistance enables the use of large emitter areas at microwave frequencies, and therefore substantial output power levels are possible from very compact devices.