A InGaP/GaAs/InGaP composite collector double heterojunction bipolar transistor (DHBT) has been designed and fabricated to combine the advantages of single heterojunction bipolar transistor (SHBT) and conventional DHBT. The device has low collector-emitter offset voltage (similar to60 mV) and knee voltage (<1V). The breakdown voltage of similar to14 V is as high as that of a conventional DHBT. Comparison was made with a GaAs homojunction bipolar transistor and InGaP/GaAs SHBT. Both homojunction transistor and composite collector DHBT show similar collector-emitter offset voltage dominated by the geometrical factor. The knee voltage of the composite collector DHBT is similar to0.15 V lower than that of the InGaP/GaAs SHBT. The results demonstrate the potential of composite collector DHBTs for practical power amplifier applications. (C) 2004 American Vacuum Society.