Automatic gain controller for radio receiver - constructed as integrated circuit without large coupling capacitor

摘要

The modification to an automatic gain control circuit for a radio receiver is intended to make it more compact by eliminating the need for large capacitors, and by constructing the controller as an integrated circuit. The amplifier (11) output (17,OUT) is also applied to two circuits (41,42) with different reference levels. The first circuit (41) operates with an alternating voltage the second (42) produces a potential above its reference level determined by the charge and discharge rate of a capacitor. The voltages produced by the two circuits are designed to overlap. The overlap is detected in a further circuit (43) which produces an output pulse whose length is proportional to the overlap time. This pulse is integrated (44) and applied to the amplifier input as a gain control signal (GC).