Output conductance of bipolar transistors with large neutral-base recombination current

Abstract

Neutral base recombination current, which is negligible in most modern bipolar transistors, can affect the common-emitter output conductance quite dramatically if it dominates other sources of base current. Mathematical theory for this phenomenon is developed, applied to some simplified special cases, and compared with numerical simulation. The large output conductance of some real Si/Si/sub 1-x/Ge/sub x/ DHBTs is seen to be the result of a large neutral base recombination current.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>