Multi-phase clock generation and synchronization
AssigneeIntel Corporation
InventorsAtila Alvandpour, Daniel Eckerbert, Ram K. Krishnamurthy
Life of this patent
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Abstract
A method for controlling a local clock includes receiving a reference clock and generating a phase-shifted version of the reference clock. The two clocks are synchronized using a closed-loop method that produces a control signal. The control signal is smoothed during the closed-loop method and the smoothed signal is then used, instead of the control signal, in generating the phase-shifted clock.
Claims27
A method of controlling a local clock, the method comprising:
- receiving a reference clock at a reference frequency;
- generating a phase-shifted version of the reference clock;
- synchronizing the reference clock and the phase-shifted version of the reference clock using a closed-loop method that generates a control signal;
- smoothing the control signal during a period of the operation of the closed-loop method to produce a smoothed control signal;
- switching from the closed-loop method to an open loop method after smoothing the control signal;
- and
- using the smoothed control signal, instead of the control signal, during at least a portion of the open loop method in generating the phase-shifted version of the reference clock.
A clock system comprising:
- a clock generator that receives a reference clock at a reference frequency and generates a phase-shifted version of the reference clock;
- a phase detector that is coupled to the clock generator, receives the reference clock, and provides a control signal indicative of a phase difference between the reference clock and the phase-shifted version of the reference clock;
- a control signal smoothing unit that is coupled to the phase detector and provides a fixed-value smoothed control signal;
- and
- a switch that is coupled to the control signal smoothing unit, the clock generator, and the phase detector, and is operable to switch the clock generator from using the control signal in generating the phase-shifted version of the reference clock to using the smoothed control signal.
A method of providing at least two phases of a reference clock the method comprising:
- receiving the reference clock;
- phase-shifting the reference clock to produce a phase-shifted reference clock;
- synchronizing the reference clock and the phase-shifted reference clock;
- and
- removing, from the phase-shifted reference clock, all phase dither attributable to the synchronizing technique while retaining phase-synchronization between the reference clock and the phase-shifted reference clock.
A method of controlling phase of a signal, the method comprising:
- providing a control signal indicative of a phase difference between a first signal and a second signal;
- controlling phase of the second signal using the control signal;
- averaging the control signal over multiple values of the control signal to produce an averaged control signal;
- and
- controlling phase of the second signal using the averaged control signal.
Dependencies are inferred from the claim text.