A VCO phase noise reduction technique to suppress the active device contribution

In this paper, a voltage-controlled oscillator (VCO) phase noise improvement technique is proposed that suppresses the phase noise contribution from the active devices. The cyclostationary noise at the VCO tail bias current source, which exhibits twice of the operation frequency, is utilized to switch the biasing transistor on and off periodically. The dc power consumption of the proposed VCO designed in 0.18 μm SiGe process is 1.03 mW with a supply voltage of 1.8 V. The simulated phase noise is -120.0 dBc/Hz at 1 MHz offset frequency and the figure-of-merit (FoM) is 179.8 dBc/Hz.