Synchronizing digital device

Abstract

A device includes a local oscillator, an all-digital phase-locked loop, a digital signal generator, sampling circuitry, and an interface. The local oscillator generates a local clock signal. The all-digital phase locked loop generates a sampling control signal. The ADPLL includes a phase-error detector, a digital filter and a sigma-delta modulator. The phase detector generates a phase error signal based on a loop clock signal and a received reference signal. The digital filter generates a signal indicative of a frequency ratio between a frequency of the reference clock signal and the local clock frequency based on the phase error signal. The sigma-delta modulator generates a modulated signal based on the signal indicative of the frequency ratio. The sampling control signal is based on the modulated signal. The sampling circuitry samples digital signals generated by the digital signal generator at a sampling frequency, which is a function of the sampling control signal.