A composite-collector InGaP/GaAs HBT with high ruggedness for GSM power amplifiers

This paper reports on an InGaP/GaAs HBT with a GaAs/InGaP composite collector for a GSM power amplifier. The GaAs/InGaP composite collector enables the device to pass a ruggedness test with SWR=10:1 at V/sub CE/ >5 V, keeping the total collector thickness of around 900 nm and with a high power added efficiency (PAE). The load-pull measurement results for multi-cell HBTs with total emitter size of 7200 /spl mu/m/sup 2/ reveals a PAE of 74% at Pout=35 dBm and V/sub CE/=3.5 V for the composite collector.