Dynamic thermal characterization and modeling of packaged AlGaAs/GaAs HBTs

In this work we show a method for the thermal dynamic modeling of packaged HBTs. The method employs a calibration step featuring pulsed measurements at different temperatures, and is based upon a 3-stage thermal resistance-capacitance model that describes the chip-solder-case system. A current pulse generator was designed and assembled in-house for pulsed characterization down to the microsecond range. The model was used to simulate the thermal transients of the collector current from the microsecond range to hundreds of seconds, for several different bias points in the forward active region, consistently showing a good match with the measured characteristics.