Patent ID: 7463106

Claim:
A push-push voltage controlled oscillator, comprising: an LC resonance unit for determining a fundamental oscillation frequency; a first negative resistance generation means connected between a first terminal and a second terminal of the LC resonance unit and configured to generate negative resistance and deliver an output signal to a first common source terminal; a first impedance element connected at one end thereof to the first common source terminal of the first negative resistance generation means and at another end thereof to the power supply VDD; a second negative resistance generation means connected in series to the first terminal and second terminal of the LC resonance unit, which are connected to the first negative resistance generation means, and configure to generate negative resistance and deliver an output signal to a second common source terminal; a second impedance element connected at one end thereof to the second common source terminal of the second negative resistance generation means and at another end thereof to a ground terminal; and an impedance adjustment unit for adjusting the impedance of the first or the second impedance element, or the overall impedance of the first and second impedance elements, wherein the impedance adjustment unit is connected to the first impedance element, the second impedance element, or both of them, so that amplitude and phase errors of differential output signals produced from the first and/or second impedance element can be minimized by comparing an amplitude and a phase mismatch at the first common source terminal with those at the second common source terminal.