Transient analysis of collector current collapse in multifinger HBT's

The authors report for the first time a time-domain analysis of thermal instability in multifinger heterojunction bipolar transistors (HBT's). This is based on a transient quasi-three-dimensional (3-D) electrothermal model that selfconsistently solves the thermal and electrical equations. This model is designed to evaluate the thermal time constant of GaAs-based power HBT's employing emitter thermal shunt and emitter ballast resistance.