Fast PNP transistor turn-off circuit

摘要

A circuit is provided for reducing the turn-off transition time of a switching PNP transistor by providing a reverse drive current to the base of the PNP transistor after the drive current has been removed from the base. The reverse drive current is generated by an NPN transistor, the emitter of which is connected to the base of the PNP transistor. A capacitor coupled to the base of the NPN transistor is charged and during the conducting period of the PNP transistor and discharged after the drive current is removed from the base of the PNP transistor to enable the base of the NPN transistor to be driven above the supply voltage connected to the emitter of the PNP transistor.