Patent ID: 7973609

Claim:
A digitally-controlled oscillator comprising: a loop-shaped transmission line path having an odd number of parallel portions in each of which two conductors are arranged in parallel to each other with a space therebetween, and an odd number of intersection portions in each of which two conductors intersect spatially; an active circuit coupled between the two conductors; and a variable capacitance unit including a plurality of variable capacitance elements coupled between the two conductors, capacitance values of the plurality of variable capacitance elements being controlled in accordance with digital control data, wherein the variable capacitance unit includes a first variable capacitance unit including a plurality of first variable capacitance elements and a second variable capacitance unit including a plurality of second variable capacitance elements, and a high capacitance state and a low capacitance state of each of the first variable capacitance elements are switched in accordance with ΣΔ-modulated control data.