An auto-ranging 50-210 Mb/s clock recovery circuit with a time-to-digital converter

This clock recovery circuit has auto-ranging. A time-to-digital converter (TDC) rather than a frequency detector is employed for accurate information about the cycle time of the incoming data. This auto-ranging circuit, which operates in the time domain, eliminates the inherent problems of harmonic locking found in conventional circuits. This circuit is configured as a triple-loop structure, which consists of a center frequency-tuning loop, a frequency detecting loop, and a phase detecting loop.