An All-Digital Approach to Supply Noise Cancellation in Digital Phase-Locked Loop

With increased levels of integration in modern system-on-chips, the coupling of supply noise in a phase-locked loop (PLL) has become the dominant source of performance degradation in many systems. In this paper, an all-digital approach to canceling the effects of supply noise is presented. By sensing the supply noise using an analog-to-digital converter (ADC), an observer-controller loop filter jointly processes the ADC and phase detector outputs to determine the oscillator control signals that minimize the output jitter. The proposed digital PLL is shown to be significantly more robust to supply noise compared with a conventional PLL.