Patent ID: 7170358
Filing Date: 2007-01-30
Classification: H03B,H03L

Abstract:
1. A voltage controlled oscillator composed of a differential circuit for oscillating a high-frequency signal, comprising: an inductor circuit having an inductor; n (n is a natural number of 2 or more) variable capacitance circuits connected in parallel with the inductor circuit, each having a variable capacitance element whose capacitance value is changed, depending on a control voltage applied, so as to feedback control an oscillation frequency; m (m is a natural number of 1 or more) high-frequency switch circuits connected in parallel with the inductor circuit, each having a capacitive element, a switching element connected to the capacitive element, and a switching control terminal through which a switching control voltage for controlling ON/OF of the switching element is input; a negative resistance circuit connected in parallel with the inductor circuit; a frequency control section of controlling ON/OFF of the switching elements of the m high-frequency switch circuits to shift a band of the oscillation frequency; and a frequency tuning sensitivity control section of adjusting a change rate of a total capacitance of the n variable capacitance circuits with respect to the control voltage, depending on the band to be used, wherein the frequency tuning sensitivity control section is connected to virtual ground points of differential signals of the n variable capacitance circuits.