Patent ID: 7310506

Claim:
A differential voltage control oscillator for oscillating a radio-frequency signal, comprising: a parallel resonance circuit in which an inductor circuit, a variable capacitance circuit, and a radio-frequency switching circuit are connected in parallel together; and a negative resistance circuit connected in parallel with the parallel resonance circuit, wherein the radio-frequency switching circuit includes: a first switching element which is switched in accordance with a control voltage applied to a first switching control terminal; a first capacitive element connected to the first switching element; a second switching element which is switched in accordance with a control voltage applied to a second switching control terminal; a second capacitive element connected to the second switching element; a control voltage terminal for supplying a common control voltage to the first and second switching control terminals, the control voltage terminal being connected to a virtual ground point for a differential signal generated in the parallel resonance circuit; a first radio-frequency signal reduction section for reducing a radio-frequency signal that flows from a conduction terminal of the first switching element to the first switching control terminal, the first radio-frequency signal reduction section being connected between the control voltage terminal and the first switching element; and a second radio-frequency signal reduction section for reducing a radio-frequency signal that flows from a conduction terminal of the second switching element to the second switching control terminal, the second radio-frequency signal reduction section being connected between the control voltage terminal and the second switching element.