A technique to stabilize the output voltage level of an emitter follower

The emitter follower configuration, which is usually driven by another amplifier stage, is discussed. Together, the preceding and emitter follower stages are modified to provide constant-output DC levels. A design method to stabilize these voltage levels is presented. Several practical circuits are illustrated. Typical results show the output DC voltage to have a temperature coefficient of only 0.6-0.7 mV/ degrees C. This constant bias maximizes transistor performance, increases signal headroom, and improves circuit stability.<
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