Multiple equilibrium points and their significance in the second breakdown of bipolar transistors

Abstract

Suggests a simple one-dimensional model for the electrical and thermal behavior of a bipolar transistor. The proposed model can be embedded in an external circuit and analyzed by an appropriate circuit analysis program. Existence of multiple equilibrium points for certain biasing conditions is demonstrated and their implication upon the transient behavior of a device is discussed. The triggering mechanism for second breakdown in the case of forward base current, as well as reverse base current, is described in the light of these multiple equilibrium points. Prediction of that part of the safe operating area boundary limited by second breakdown is reported. The results compare favorably with the manufacturer's recommended limit.