RF small signal avalanche for bipolar transistor circuit design: Characterization, modeling and repercussions

In the face of increasing demands for high frequency and high output power of modern bipolar transistor circuits, electronic circuit designers are exploring regimes of transistor operation that meet both requirements and enter RF regimes, where impact ionization is significant. The present paper addresses AC/RF avalanche characterization techniques. Repercussions of avalanche breakdown on some important transistor properties like unilateral power gain and the stability factor are introduced and demonstrated by measurements on modern industrial devices. On the basis of theoretical considerations and compact model simulations it is shown when avalanche can be expected to have significant impact on AC performance of bipolar transistors.