Systems and methods involving phase detection with adaptive locking/detection features
Systems and methods associated with control of clock signals are disclosed. In one exemplary implementation, there is provided a delay-lock-loop (DLL) and/or a delay/phase detection circuit. Moreover, such circuit may comprise digital phase detection circuitry, digital delay control circuitry, analog phase detection circuitry, and analog delay control circuitry. Implementations may include configurations that prevent transition back to the unlocked state due to jitter or noise.
1. A method for detecting and adaptively locking phase of circuitry, the method comprising:
detecting an input signal phase of a reference clock and an output signal phase of a feedback clock;
reducing a rate of the input signal phase and a rate of the output signal phase by a first amount, M;
comparing one or both of a rising edge and/or a falling edge of the reduced rate of the reference clock to a rising edge and/or a falling edge of the reduced rate of the feedback clock;
adjusting, via a digital adjustment mode, the feedback clock until the output signal phase is approximately equal to the input signal phase;
when the output signal phase is approximately equal to the input signal phase, entering an analog adjustment mode which includes reducing the rate of the input signal phase and the rate of the output signal phase by a second amount, N;
adjusting the output signal until the output signal phase is equal to the input signal phase, whereupon the circuitry changes from an unlocked state to a locked state.
2. The method of claim 1 further comprising one or more of:
comparing a leading or rising edge of the reduced rate reference clock to a leading or rising edge of the reduced rate feedback clock;
comparing a trailing or falling edge of the reduced rate reference clock to a trailing or falling edge of the reduced rate feedback clock; and/or
continuing the analog adjustment mode after the locked state is reached, including widening a phase detection window, which enables ability to hold the circuitry in the locked state when the circuitry is experiencing jitter or noise, thereby reducing spurious transition back to the unlocked state.
3. The method of claim 1 , wherein the analog adjustment mode is continued after the locked state is reached and includes utilization of a widened phase detection window, which enables improved ability to hold at a lock state when experiencing jitter or noise thereby reducing spurious transition back to the unlocked state.
4. The method of claim 1 , further comprising:
performing digital adjustment of phase including digital phase delay until the feedback clock phase is within a first window of the reference clock phase;
holding the digital phase delay; and
performing analog adjustment of phase until the feedback clock phase is equal to the reference clock phase.
5. The method of claim 1 , further comprising one or both of:
widening a second detection window during the analog detection mode to facilitate maintaining a lock; and/or
widening the second detection window via moving a rising or leading edge of the second detection window earlier.
6. The method of claim 1 , further comprising moving a leading edge of a phase detection window earlier via bypassing a circuit in a path of the reference clock.
7. The method of claim 1 , wherein widening a second detection window is achieved via moving a trailing edge of the second detection window later.
8. The method of claim 1 , further comprising moving a falling or trailing edge of a phase detection window later via adding an extra delay circuit or circuitry in a path of the reference clock.
9. The method of claim 1 , further comprising detecting the phase via a first phase detection window having a duration of between about 50 to about 900 picoseconds.
10. The method of claim 1 , further comprising detecting the phase via a first phase detection window having a width established as a function of a frequency of the input signal, of a magnitude on scale with between about 100 to about 200 picoseconds for an input signal in a frequency range of about 100 MHz to about 2 GHz.
11. The method of claim 1 , further comprising, in analog adjustment mode and during lock, widening a phase detect window within which the phase is detected to reduce unwanted transition back to the unlocked state caused by spurious effects on the circuitry, such as jitter or noise.
12. The method of claim 1 , wherein a clock rate is reduced to provide a wider phase detect margin during the analog adjustment mode and the locked state to insulate from jitter or noise.
13. The method of claim 1 , wherein a clock rate is reduced during the analog adjustment mode and the locked state to insulate from jitter or noise.
14. The method of claim 1 , wherein a phase detection window of the digital adjustment mode is widened by one or both of:
shifting a rising or leading edge of the phase detection window earlier; and/or
shifting a falling or trailing edge of the phase detection window later.
15. The method of claim 1 , wherein a first or leading edge of a phase detection window is shifted earlier via reducing or eliminating delay in a circuit path associated with the digital adjustment mode or the analog adjustment mode.
16. The method of claim 15 , wherein the reducing or eliminating delay includes removing or bypassing a circuit that provides delay.
17. The method of claim 1 , wherein a second or trailing edge of the detection window is shifted later via introduction of delay or multiplexing circuitry.
18. The method of claim 1 , wherein delay associated with adjusting the output signal phase to match the input signal phase is introduced by adding an extra delay circuit via multiplexing the output signal.
19. The method of claim 1 , wherein the rate of the output signal phase is decreased via introduction of divide-by-N circuitry, divide-by-3 circuitry, or divide-by-4 circuitry.
20. The method of claim 1 further comprising shifting a second or trailing edge of a detection window, in which the output signal phase is compared to the input signal phase, later via introducing delay during to digital adjustment mode.
21. The method of claim 1 wherein the analog adjustment mode, including utilization of a widened phase detection window, is continued after the locked state is reached to maintain the locked state.
22. The method of claim 1 further comprising reducing frequency of the output signal associated with the feedback clock and/or reducing frequency of the input signal associated with the reference clock.
23. The method of claim 1 further comprising feeding the reference clock through a frequency reduction component during the analog adjustment mode to widen a phase detect window.
24. The method of claim 23 wherein the frequency reduction component includes a divide-by-N circuit, a divide-by-3 circuit, or a divide-by-4 circuit.
25. The method of claim 1 further comprising providing, in a circuit path of the feedback clock, a divide-by-N circuit, a divide-by-3 circuit, or a divide-by-4 circuit, through which the feedback clock is fed during an adjustment mode to widen a phase detection window.
26. The method of claim 1 further comprising providing, in a circuit path of the reference clock, a divide-by-N circuit, a divide-by-3 circuit, or a divide-by-4 circuit, through which the reference clock is fed during an adjustment mode to widen a phase detection window.