VARIABLE CAPACITANCE CIRCUIT

摘要

A circuit having a variable input impedance which is controlled by application of a direct current input signal. The variable impedance circuit comprises a pair of capacitors coupled in series with a pair of diodes. The diodes are rendered conductive in response to the direct current control signal to substantially short the two capacitors in series with one another across the input terminals of the circuit. With no direct control signal being applied to the circuit the diodes are non-conductive which substantially disconnects the capacitors from appearing across the inputs of the circuit. Hence, the reactance component of the input impedance of the circuit is varied in response to the direct control signal.