Electro-thermal coupling simulation of high power bipolar transistors

It is shown that a numerical iterative coupling process between an electrical model of high power bipolar transistors and a three-dimensional thermal model (based on the thermal influence coefficient method) of the transistor and its case well predicts the onset of an electro-thermal instability in this kind of devices. The presented calculation procedure can supply a useful tool for the design of an optimized thermal environment in order to improve the DC SOA of high power bipolar transistors.