Automatic gain control circuit utilizing voltage variable capacitor

Claim 1

IN A RADIO WAVE RECEIVER INCLUDING A SOURCE OF SIGNALS SUBJECT TO AMPLITUDE VARIATIONS AND A PRODUCT DETECTOR HAVING A DIRECT CURRENT OUTPUT VOLTAGE, THE AMPLITUDE OF WHICH IS A FUNCTION OF SAID SIGNALS, A VARIABLE IMPEDANCE COUPLING CIRCUIT, COMPRISING: A SIGNAL HANDLING CHANNEL HAVING AN INPUT CONNECTED WITH SAID SIGNAL SOURCE AND AN OUTPUT CONNECTED WITH SAID PRODUCT DETECTOR, SAID SIGNAL HANDLING CHANNEL INCLUDING A SERIES LEG AND A SHUNT LEG, SAID OUTPUT BEING CONNECTED ACROSS SAID SHUNT LEG; A VOLTAGE VARIABLE CAPACITOR CONNECTED IN ONE OF SAID LEGS; A CAPACITOR CONNECTED IN THE OTHER OF SAID LEGS, THE AMPLITUDE OF THE OUTPUT SIGNAL DERIVED FROM THE OUTPUT OF SAID CHANNEL BEING A FUNCTION OF THE RATIO OF THE CAPACITY OF SAID CAPACITORS; AND AN AUTOMATIC CONTROL CIRCUIT CONNECTING THE DIRECT CURRENT OUTPUT VOLTAGE OF SAID PRODUCT DETECTOR WITH SAID VOLTAGE VARIABLE CAPACITOR TO VARY THE CAPACITY THEREOF, TO CONTROL THE OUTPUT OF THE VOLTAGE DIVIDER WITH VARIATIONS OF THE AMPLITUDE OF SAID SIGNAL.