Patent ID: 7626470

Claim:
A multi-band voltage-controlled oscillator an inductor connected to a first output terminal and a second output terminal; a first switch controlled based on an operating frequency band; a coarse tuning unit determining a coarse operating frequency band based on a capacitance; main fine tune branch connected to the first and second output terminals, and whose capacitance varies according to a tuning voltage; and an auxiliary fine tune branch connected to the first and second output terminals, and whose capacitance varies according to the tuning voltage when the first switch is turned on and whose capacitance does not vary when the first switch is turned off; and a tuning voltage terminal to which the tuning voltage is applied, wherein the main fine tune branch comprises: a first varactor connected between the tuning voltage terminal via a first resistor, and a first voltage terminal; and a second varactor connected between the tuning voltage terminal via a second resistor, and the first voltage terminal, wherein the auxiliary fine tune branch comprises: a third varactor connected between a first terminal of the first switch via a third resistor, and the first voltage terminal; and a fourth varactor connected between the first terminal of the first switch via a fourth resistor, and the first voltage terminal, and a second terminal of the first switch is connected to the tuning voltage terminal.