This paper describes a 1V, 1GHz low-noise phase locked- loop (PLL) using a noise-rejected voltage-controlled ring oscillator (VCO). In order to improve the power consumption and oscillation frequency of the PLL, we design the VCO with a new structure of the delay cell. This VCO consists of four-stage fully differential delay cells with the pre-charged scheme that can obtain the characteristics of high speed and low voltage operation. And the bias generator circuit can increase the tuning range and tuning linearity of VCO. The HSPICE simulation results are based upon TSMC 0.18μm 1P6M N-well CMOS process. The simulation results show that the VCO can operate from 50 to 1100 MHz, and when the input control voltage is 0.6V, the oscillation frequency is 1GHz. The power consumption of the PLL is 1.092mW at a supply voltage of 1V.