Push=pull amplifier with two output stages - has input difference stage and current or power source for setting closed circuit current and no-load amplification

摘要

The push-pull amplifier has tow output stages whose output transistors, connected together form the output of the amplifier, an input difference stage and a current or power source for setting the closed circuit current and the no-load amplification. The control current (Ist) from the control current source feeds the difference stages, one output controlling the output stage, and two controlled transistors (Q1, Q2) are provided with their bases connected together. One of these transistors supplies the output of the difference stage and the toher transistor the other output. The control current flows through the difference stage to the two transistors (Q3, Q4) with the base current provided by an emitter follower (Q5) and its base at a node point. ADVANTAGE - Simple method of controlling output stages and a low and stable closed circuit current.