An oscillator includes a plurality of varactor cells to receive a control signal to control a frequency of the oscillator. Each of the varactor cells includes a switch that includes a first terminal to receive the control signal and a second terminal such that the switch operates to control a capacitance of the varactor cell in response to a voltage between the first and second terminals. The oscillator includes a bias circuit to provide a different bias voltage to each second terminal and an amplifier that is coupled to the varactor cells to generate an oscillating signal.