SOA reduction due to combined electrothermal and avalanche effects in multifinger bipolar transistors

The impact of the concurrent action of electrothermal and avalanche effects on the reduction of the safe operating area is experimentally investigated for a wide number of single-, two-, and three-finger bipolar transistors fabricated in SiGe, GaAs, and silicon-on-glass technologies. The analysis is substantiated by a SPICE-like simulation tool that allows monitoring of the temperatures of the individual fingers and provides an in-depth understanding of the separate influence of these positive feedback mechanisms on the device operation.