Abstract: A method for calibrating a phase locked loop (PLL) includes counting cycles of an output clock signal generated by the PLL until early phase lock signal is asserted when the cycles of the output clock signal counted within a first duration of time differ from a first target value by no more than a first maximum difference, counting cycles of the output clock signal until final phase lock signal is asserted when the cycles of the output clock signal counted within a second duration of time differ from a second target value by no more than a second maximum difference, the second duration of time being greater than the first duration of time, and using the output clock signal to control an operation in a physical layer circuit of a communication interface after the early phase lock signal is asserted and before the final phase lock signal is asserted.

Abstract: A data communication interface has a delay-locked loop configured to generate a receive clock signal based on timing information provided by a signal received over a clock channel of a data communication link, a phase interpolator configured to provide a phase-shifted clock signal by phase-shifting one or more edges in the receive clock signal based on timing of transitions in a data signal received over a data channel of the data communication link, a clock and data recovery circuit configured to capture data from the data signal using the phase-shifted clock signal, and a calibration circuit. The calibration circuit is configured to calibrate the delay-locked loop while the clock and data recovery circuit is in an idle state, recalibrate the delay-locked loop when the clock and data recovery circuit is activated, and calibrate the clock and data recovery circuit after recalibrating the delay-locked loop.

Abstract: A phase locked loop (PLL) method includes generating a first signal based on a comparison of a phase of a reference clock or signal to a phase of a feedback clock; generating an output clock based on the first signal; generating an intermediate feedback clock including frequency dividing the output clock; fractionally frequency dividing the intermediate feedback clock based on a digital control signal to generate the feedback clock; and generating the digital control signal based on a sampling clock having a frequency greater than a frequency of the feedback clock. In one implementation, a PLL includes a frequency multiplier to generate the sampling clock based on the feedback clock. In another implementation, a PLL uses the intermediate feedback clock as the sampling clock.

Abstract: A phase locked loop (PLL) method includes generating a first signal based on a comparison of a phase of a reference clock or signal to a phase of a feedback clock; generating an output clock based on the first signal; generating an intermediate feedback clock including frequency dividing the output clock; fractionally frequency dividing the intermediate feedback clock based on a digital control signal to generate the feedback clock; and generating the digital control signal based on a sampling clock having a frequency greater than a frequency of the feedback clock. In one implementation, a PLL includes a frequency multiplier to generate the sampling clock based on the feedback clock. In another implementation, a PLL uses the intermediate feedback clock as the sampling clock.

Abstract: A method for fixing a dead-zone in a clock and data recovery (CDR) circuit is disclosed herein. The CDR circuit includes a CDR block and a phase interpolator, the CDR block is configured to generate phase codes based on signals from a phase detector, and the phase interpolator is configured to adjust a phase of a clock signal based on the phase codes. The method includes waiting for the CDR circuit to lock, reading a first phase code from the CDR block, changing the first phase code by a first amount to obtain a second phase code, and inputting the second phase code to the phase interpolator.

Abstract: A method for fixing a dead-zone in a clock and data recovery (CDR) circuit is disclosed herein. The CDR circuit includes a CDR block and a phase interpolator, the CDR block is configured to generate phase codes based on signals from a phase detector, and the phase interpolator is configured to adjust a phase of a clock signal based on the phase codes. The method includes waiting for the CDR circuit to lock, reading a first phase code from the CDR block, changing the first phase code by a first amount to obtain a second phase code, and inputting the second phase code to the phase interpolator.