Biassing circuit for push-pull circuits - reduces temp. and supply fluctuations using two transistors and two diodes

摘要

The biasing circuit is particularly intended for a voltage controlled circuit with variable amplification. It consists of two cascaded transistors of the same conductivity and two series diodes, formed by parts of two transistors, forward biased by part of the drive current passing to the two transistors. A voltage is applied via the series diodes between the bases of the two transistors. The emitters of the transistors are connected to a following class B pushpull circuit. Preferably a current bypass is provided across the two diodes to the first transistor emitter. The advantage lies in reducing temp. and supply variations in the biasing of pushpul circuits.