Fully integrated 9 GHz CMOS VCO with very low phase noise

A fully integrated CMOS voltage-controlled oscillator (VCO) with very low phase noise is presented in this paper. Two filters were employed at top and bottom of the VCO core to maximize the voltage swing and to suppress flicker noise up-conversion. The measured phase noise at 1 MHz offset from a 9.3 GHz carrier is better than -126 dBc/Hz. And the phase noise variation over the whole tuning range (8.8 to 9.4 GHz) is as small as 3 dB. The VCO core consumes 32 mW from a 4.5 V supply. To the authors' knowledge, this is the lowest phase noise at 1 MHz offset for a silicon-based fully integrated VCO in this frequency range. The excellent phase noise performance makes the VCO especially suited for satellite communications.