Feedback signal amplifier

摘要

A feedback signal amplifier circuit having switchable closed loop gain in response to the output signal level of the amplifier for limiting the output signal level is presented. The feedback ratio of the circuit is switched by output signal level responsive diodes which derive signal level determining bias from both an unregulated power supply and the output terminal of the amplifier. A bias compensation network deriving bias from the unregulated power supply is connected to a bias sensitive input of the amplifier for tracking changes in power supply voltage which are reflected into the output of the amplifier for keeping the signal level determining bias of the diodes essentially constant and independent of changes of power supply voltage.