Large Signal Characterization of HBT´s for Microwave Applications, including Self-Heating Effects

This paper presents a unified analytical large signal model including self-heating effects, for an AlGaAs/GaAs heterojunction bipolar transistor (HBT). The self-heating effect in the HBT is simulated as a feedback from the collector current to the base-emitter voltage. The main advantage of the circuit presented here is that additional analysis of coupling between electrical and thermal circuits is not required as is the case with the existing models. The large signal model is based on the measured forward Gummel-Poon plot and is built over the small-signal model. Both the small signal and large signal models are implemented in the commercial simulator, LIBRA, and verified by comparing the simulated and measured characteristics of the HBT.