Monotonic Wide-Range Digitally Controlled Oscillator Compensated for Supply Voltage Variation

A digitally controlled oscillator (DCO) to be used in an all-digital phase-locked loop (PLL) is presented which offers a wide operating frequency range, a monotonic gain curve, and compensation for instantaneous supply voltage variation. The monotonic and wide oscillation frequency is achieved by interpolating at the fine tuning block between two nodes selected from a coarse delay line. Supply voltage compensation is obtained by dynamically adjusting the strength of the feedback latch of the delay cell in response to the change of the supply voltage.