Patent ID: 7375596

Claim:
A quadrature voltage controlled oscillator comprising: a first voltage controlled oscillator which outputs a positive in-phase output signal and a negative in-phase output signal; a second voltage controlled oscillator which outputs a positive quadrature-phase output signal and a negative quadrature-phase output signal, the second voltage controlled oscillator having a symmetrical structure with the first voltage controlled oscillator and constituting a feedback loop together with the first voltage controlled oscillator; a first constant current source which supplies constant current to the first voltage controlled oscillator in response to the output signals from one of the first and second voltage controlled oscillators; and a second constant current source which supplies constant current to the second voltage controlled oscillator in response to the output signals from one of the first and second voltage controlled oscillators, wherein the first constant current source is capable of supplying constant current to the first voltage controlled oscillator in response to at least the output signals from the first voltage controlled oscillator.