A low-phase-noise low-phase-error 1.8 GHz quadrature CMOS VCO

A 1.8 GHz quadrature VCO in standard 0.35 /spl mu/m CMOS with three metal layers shows -140 dBc/Hz or less phase noise across an 18% tuning range, while drawing 25 mA from a 2 V power supply. The quadrature phase error between the VCO outputs is at most 0.25/spl deg/.