Heating in multi-emitter SiGe HBTs

Bipolar transistors with multiple emitters are used to achieve high currents and the maximum utilization of emitter area. The multi-emitter SiGe HBTs fabricated in a modified Si BiCMOS technology is studied in this paper. The heating and thermal coupling between the emitters of a multiple emitter SiGe HBT were measured along the emitter length. This measurement provides useful information about the temperature increases in multi-emitter devices and the emitter-emitter thermal coupling. Temperature dependence of the normalized emitter currents and power dependence of the monitored emitter currents were studied through experiments.