Multiplying delay-locked loop using sampling time-to-digital converter

摘要

A multiplying delay-locked loop circuit includes a delay chain including a plurality of variable delay circuits connected in series and having a delay chain output, and a feedback loop including circuitry for deriving a digital control signal representing magnitude and sign of phase offset in the delay chain output, for controlling delay in ones of the variable delay circuits. The circuitry for deriving a digital control signal includes a sampling time-to-digital converter (STDC) configured to operate on a time delay between inputs to generate the digital control signal. The STDC subtracts a second difference the signals derived from the delay chain output and output of the feedback divider from a first difference between the signals derived from the delay chain output and output of the feedback divider to provide a difference value, and the difference value indicates sign and magnitude of output offset in the delay chain output.