HIGH-GAIN, PULSED-POWER ALGAAS GAAS HBTS

A layout to minimize parasitic elements which reduce the common emitte r Heterojunction Bipolar Transistor (HBT) gain and efficiency is descr ibed. Layout modifications are based upon consideration of the HBT dev ice model that predicts better performance by reducing feedback elemen ts. Reducing the base contacts size to minimize extrinsic base-collect or capacitance, and reducing inductance in the ground connection are t he primary paths to better performance. The improvements in small sign al and power performance for several HBT variations are described. The changes result in a 320 mu m(2) emitter area HBT which operating puls ed at 10 GHz delivers 1.25 W output power with 10.5 dB associated gain and 56% power-added efficiency.