Patent ID: 8222963

Claim:
A voltage-controlled oscillator comprising: a resonator section in which a plurality of types of variable capacitance elements having different structures and capacitance variation characteristics are connected in parallel and capacitance values of said plurality of types of variable capacitance elements are controlled simultaneously by a control voltage; and an amplifier section that maintains oscillation produced by said resonator section, wherein the resonator section comprises: an inductor; a first MOS varactor and a second MOS varactor connected between respective ones of two ends of said inductor and a common node; a first varactor diode and a second varactor diode connected between respective ones of two ends of said inductor and a power supply so as to be reverse biased; a first resistor connected between the common node and a voltage control terminal; a second resistor and a third resistor connected between respective ones of two ends of said inductor and the voltage control terminal; and a third varactor diode and a fourth varactor diode which, when the power supply is one of either a high-potential power supply or a low-potential power supply, are connected between the other one of these power supplies and respective ones of two ends of said inductor so as to be reverse biased.