Dynamic electrothermal analysis of bipolar devices and circuits relying on multi-port positive fraction Foster representation

In this paper, a novel multi-port RC network is proposed to describe the dynamic thermal feedback in bipolar devices/circuits with multiple heat sources. The parameters of the circuit can be reliably identified by standard electrical macro-modeling techniques. The representation is shown to be more compact than the usual Foster topology due to the limited number of dynamic elements. The approach is successfully applied to predict thermally-triggered hogging phenomena in basic bipolar differential amplifiers subject to considerable thermal effects.