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A wideband LC VCO used in low power and phase noise applications is described. A phase noise model is utilized for its lower phase noise design. A switched capacitor array, two power supply and substrate noise filters are involved in the circuit. The phase noise imported by the MOS channel current and tank less resistance is modeled to give approximate evaluation of the circuit performance. The circuit has been implemented in a standard 65 nm CMOS technology. The test result indicates that the frequency of the VCO is from 750 MHz to 1.5 GHz, and the phase noise is -125.84 dBc/Hz @1 MHz in 1.21GHz. The chip consumes less than 2.25 mW with 1.2 V power supply, and occupies 0.7 mm2 areas.