A 6–11GHz multi-phase VCO design with active inductors

A multiphase VCO using differential active inductors is designed and fabricated in an IBM 0.13 um CMOS process. Using active inductors, the core VCO occupies 0.3times0.4 mm , and the central frequency can vary from 6 GHz to 11 GHz, exhibiting a 58% tunable frequency ranges. Exploiting current reuse, the phase noise is measured to be less than -95 dBc/Hz at 1 MHz offset with the measured power consumption ranging from 12 to 31 mW in 6-11 GHz. A signal coupling technique with phase shifting is employed to generate eight phase signals. The achieved phase errors of this design are smaller than 3deg. In addition, bias compensation is shown to reduce the frequency variation under 10% while the temperature varies from -55degC to 125degC.