Base drive circuit for high-power switching transistor

摘要

Disclosed is a base drive circuit (10-1, 10-2) that provides a base drive current particularly adapted to switch a switching power transistor (QA, QB) ON and OFF quickly. The base drive current includes a variable AC impedance device that responds to a control pulse to form a base drive having (a) an initial forward base drive peak that drives the switching power transistor toward deep saturation momentarily, followed by (b) an intermediate drive current of lower magnitude, sufficient to keep a high-power transistor at or near saturation, and (c) a high-amplitude reverse drive current for high-speed turn-off of the transistor.