A computer model for lateral thermal instabilities in power transistors

A three-dimensional mathematical model is described which approximates the nonlinear lateral thermal feedback mechanisms producing hot spot formation in power transistors. The model satisfactorily predicts many features of the hot spot phenomenon which are observed experimentally. Providing a capability for assessing the merits of various emitter stripe configurations, as well as two forms of emitter ballasting, it represents a first step toward the achievement of a computer-aided engineering tool for power transistor design.