Thermal Effect and Frequency Response Analyses on Heterojunction Bipolar PowerTransistor

摘要

Heterojunction bipolar transistors (HBT) based on Npn AlGaAs/GaAs material systemhave attracted considerable attention for microwave power and digital applications dueto their high speed and high current capabilities. In this paper, a numerical model basedon the Npn AlGaAs/GaAs HBT structure for the carrier transport is presented. Threefigures of merit on device operation, current gain, cut-off frequency and maximumoscillation frequency are calculated. Besides, thermal instability plays an importantrole on power HBT resulted from the low thermal conductivity in GaAs. Thegenerated heat will increase the junction temperature and cause self-destruction.Therefore, the thermal runaway study of the junction temperature, current–voltage(IV) characteristics and frequency response using an analytical thermal model isdescribed.