Current gain long-term instability of AlGaAs/GaAs HBT: physical mechanism and SPICE simulation

The current gain instability of AlGaAs/GaAs heterojunction bipolar transistor (HBT) is investigated, and a new AlGaAs/GaAs HBT model for SPICE circuit simulation is presented. Such a model includes the effects of base and collector leakage currents and the stress-induced abnormal base current, thus allowing the simulation of the performance of HBT circuits subjected to the electrical/thermal stress test (i.e. burn-in test).