InGaP/GaAs power HBTs with a low bias voltage

This paper describes InGaP/GaAs heterojunction bipolar transistors (HBTs) for L-band power amplifiers with low bias voltage. A fabricated HBT with an emitter size of 2 /spl mu/m/spl times/20 /spl mu/m/spl times/64 fingers offers an output power, Pout, of 34.3 dBm and a power added efficiency, /spl eta//sub add/, of 57.7 % at 1.5 GHz with a collector bias of 3.5 V under class AB operation. The power HBT indicates an output power of over 31 dBm at a bias of as low as 2.5 V. Adjacent channel power leakage of the power HBT according to the Japanese standards of personal digital cellular phone (PDC) is -49 dBc when Pout is 31.4 dBm and /spl eta//sub add/ is 50.3% with collector bias of 3.5 V. This performance shows that InGaP/GaAs HBT is a useful device with a low bias voltage.