Patent ID: 8339211

Claim:
A voltage-controlled oscillator, comprising: a first voltage-controlled oscillator circuit having a first output and a second output; and a second voltage-controlled oscillator circuit having a third output and a fourth output, the first voltage-controlled oscillator circuit and the second voltage-controlled oscillator circuit being coupled to a voltage source in parallel, and the first, second, third, fourth outputs generating quadrature-phase oscillating signals; wherein the first voltage-controlled oscillator circuit comprises: a first inductor having a first end and a second end, the first end of the first inductor being coupled to the voltage source, and the second end of the first inductor being the first output; a second inductor having a first end and a second end, the first end of the second inductor being coupled to the voltage source, and the second end of the second inductor being the second output; a first variable capacitor having a first end and a second end, the first end of the first variable capacitor being coupled to a first control voltage, and the second end of the first variable capacitor being coupled to the second end of the first inductor; a second variable capacitor having a first end and a second end, the first end of the second variable capacitor being coupled to the first control voltage, and the second end of the second variable capacitor being coupled to the second end of the second inductor; a third inductor having a first end and a second end, the first end of the third inductor being coupled to the second end of the first inductor; a fourth inductor having a first end and a second end, the first end of the fourth inductor being coupled to the second end of the second inductor; a first MOS transistor having a first end coupled to the second end of the third inductor, a gate terminal coupled to the second end of the second inductor, and a second end being grounded; and a second MOS transistor having a first end coupled to the second end of the fourth inductor, a gate terminal coupled to the second end of the first inductor, and a second end being grounded; wherein a circuit configuration of the second voltage-controlled oscillator circuit is identical to that of the first voltage-controlled oscillator circuit, and the third output and the fourth output are arranged at nodes corresponding to the nodes of the first output and the second output.