Patent ID: 7696830

Claim:
A digital controlled oscillator comprising: an oscillator unit including a variable capacitance section having a first capacitor unit and a second capacitor unit and generating a signal having an oscillation frequency corresponding to a capacitance value of the variable capacitance section, the first capacitor unit including a plurality of first variable capacitors selectable between a first capacitive state and a second capacitive state larger in capacitance value than the first capacitive state, the second capacitor unit including a plurality of second variable capacitors selectable between a third capacitive state and a fourth capacitive state larger in capacitance value than the third capacitive state, wherein a first change amount as a difference in capacitance value between the first capacitive state and the second capacitive state is a value obtained by multiplying a second change amount as a difference in capacitance value between the third capacitive state and the fourth capacitive state by an integer equal to or more than 2, and the plurality of the first variable capacitors have the same first change amount as one another, and each of the second variable capacitors included in the second capacitor unit is controlled with ΣΔ modulation.