Design simulation and measurement of high efficiency microwave power heterojunction bipolar transistors

In this paper we describe the design, simulation and measured performance of high efficiency power HBTs. Devices with emitter lengths of 1.7mm operated under pulse bias (0.2μs, 1% duty cycle) can deliver output powers at 1 dB gain compression of up to 8W at 4GHz. The associated gain is 5dB and the peak power added efficiency around 40%. This represents the highest power reported for a power HBT.