A Low Phase Noise Wideband Voltage-Controlled Oscillator Applied in Frequency Synthesizers

A wideband LC voltage-controlled oscillator (VCO) based on a switched-capacitor array structure is designed using a 0. 18 µm BiCMOS process. The effects of key parameters on phase noise are also analyzed. Based on the analysis of the quality factor of the LC resonant loop in the VCO, the resonant loop is optimized and the quality factor of the resonant loop is improved to reduce the phase noise of the VCO. The noise filtering technique is used to reduce the influence of the tail current source noise on the phase noise of the VCO. The post-simulation results show that the designed voltage-controlled oscillator operates within a frequency range of 6.44GHz to 8.03 GHz, achieving a phase noise of -119.4 dBc/Hz at 8.03 GHz with a frequency offset of 1 MHz.