Variable capacitance circuit having on/off switch for variable capacitance function, and voltage controlled oscillator using the variable capacitance circuit

摘要

A variable capacitance circuit capable of switching on and off a variable capacitance function, includes variable capacitance means formed such that variable capacitance elements whose capacitance values change according to a voltage value of a supplied capacitance control voltage are connected so as to be paired and a plurality pairs of variable capacitance elements are connected in parallel forming multiple stages; bias voltage generation means for generating bias voltages of different voltage values based on a constant voltage from a constant voltage source; and an on-off switch for the variable capacitance function, in which the variable capacitance function of the variable capacitance means is turned on by supplying the bias voltage to the variable capacitance element of each stage of the variable capacitance means and turned off by grounding the bias voltage of each voltage value.