Abstract: To provide a voltage controlled oscillator capable of being treated as a lumped constant circuit, having small size and capable of obtaining an oscillation frequency in a high frequency band. A resonance part in a voltage controlled oscillator has variable capacitance elements whose electrostatic capacitance varies in accordance with a control voltage for frequency control input from the outside and an inductance element, an amplifying part amplifies a frequency signal from the resonance part, and a feedback part, having feedback capacitance elements, forms an oscillation loop together with the amplifying part and the resonance part by making the frequency signal amplified in the amplifying part to be fed back to the resonance part. Further, the resonance part and the feedback part are provided on a quartz-crystal substrate.

Abstract: To provide a voltage controlled oscillator capable of being treated as a lumped constant circuit, having small size and capable of obtaining an oscillation frequency in a high frequency band. A resonance part 1 in a voltage controlled oscillator has variable capacitance elements 13, 14 whose electrostatic capacitance varies in accordance with a control voltage for frequency control input from the outside and an inductance element 11, an amplifying part 21 amplifies a frequency signal from the resonance part 1, and a feedback part 2, having feedback capacitance elements 22, 23, forms an oscillation loop together with the amplifying part 21 and the resonance part 1 by making the frequency signal amplified in the amplifying part 21 to be fed back to the resonance part 1. Further, the resonance part 1 and the feedback part 2 are provided on a quartz-crystal substrate 5.