A low phase noise quadrature LC VCO in CMOS technology

A quadrature LC VCO is designed and fabricated using a standard 0.18 /spl mu/m CMOS process. The oscillation frequency can be tuned from 1400 to 1530 MHz through a 2-bit switched capacitor array. The measured free running phase noise is -125.04 dBc/Hz at 600 kHz offset from the 1.52 GHz carrier. The measured harmonic distortion is below -26 dBc. The designed VCO has achieved the figure of merit (FOM) of -185.4 dBc/Hz, which is the best among the compared VCOs with on-chip inductors using a standard CMOS process.