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

A multiphase VCO using differential active inductors is designed and fabricated in an IBM 0.13um CMOS process. Using active inductors, the core VCO occupies 0.3x0.4 mm², and the central frequency can vary from 6GHz to 11GHz, exhibiting a 58% tunable frequency ranges. Exploiting current reuse, the phase noise is measured to be less than -95dBc/Hz at 1MHz offset with the measured power consumption ranging from 12 to 31mW in 6-11GHz. A signal coupling technique with phase shifting is employed to generate eight phase signals. The achieved phase errors of this design are smaller than 3°. In addition, bias compensation is shown to reduce the frequency variation under 10% while the temperature varies from -55°C to 125°C.