A voltage-controlled oscillator (VCO) of ring-connected stages, where each stage in the VCO has a first set of differential inverters biased by variable bias voltages, and a second set of differential inverters biased by fixed bias voltages. The differential inverters in each stage are connected in parallel with each other. Each set of differential inverters in a stage may contain only one differential inverter. The variable bias voltages are provided by charge pumps and associated circuits as used in well-known self-biasing schemes for phase locked loops. The fixed bias voltages are provided by a biasing circuit, matched to the circuits associated with the charge pumps, but where a fixed control voltage is applied to provide the fixed bias voltages.