Delay line synchronizer apparatus and method
First Claim
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1. A method for adjusting a delay of an adjustable delay, comprising:
- decoupling an input of the adjustable delay from receiving an input clock signal;
decoupling an output of the adjustable delay from providing an output clock signal;
after decoupling the adjustable delay, adjusting the delay from a current delay to a new delay;
recoupling the output of the adjustable delay;
recoupling the input of the adjustable delay to receive the input clock signal; and
while the input of the adjustable delay is decoupled, tracking an edge relationship of a reference clock signal and the input clock signal having a different clock frequency than the reference clock signal, the input clock signal provided to the adjustable delay and maintaining the edge relationship after recoupling the input and output of the adjustable delay.
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Abstract
A synchronizer system and method that can be used with a conventional adjustable delay circuit to preserve a pseudo-synchronous phase relationship between clock signals of different clock domains when the time delay of the adjustable delay circuit from which one of the clock signals is output is changed.
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Citations
28 Claims
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1. A method for adjusting a delay of an adjustable delay, comprising:
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decoupling an input of the adjustable delay from receiving an input clock signal; decoupling an output of the adjustable delay from providing an output clock signal; after decoupling the adjustable delay, adjusting the delay from a current delay to a new delay; recoupling the output of the adjustable delay; recoupling the input of the adjustable delay to receive the input clock signal; and while the input of the adjustable delay is decoupled, tracking an edge relationship of a reference clock signal and the input clock signal having a different clock frequency than the reference clock signal, the input clock signal provided to the adjustable delay and maintaining the edge relationship after recoupling the input and output of the adjustable delay. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for generating a clock signal, comprising:
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receiving a clock signal in a first clock domain; generating a clock signal in a second clock domain having a phase relationship relative to a clock edge of the clock signal in the first clock domain, the clock signal in the second clock domain having a higher frequency than the clock signal in the first clock domain; ceasing generation of the clock signal in the second clock domain; adjusting the phase relationship between the clock signals in the first and second clock domains to a new phase relationship while generation of the clock signal in the second clock domain is ceased; and generating the clock signal in the second clock domain having the new phase relationship relative to the clock edge of the clock signal in the first clock domain. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a memory device, comprising:
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latching data in response to a delayed clock signal, the delayed clock signal provided by an adjustable delay; adjusting a delay of the adjustable delay, comprising; decoupling an input of the adjustable delay from receiving an input clock signal; after decoupling the adjustable delay, decoupling an output of the adjustable delay from providing an output clock signal; adjusting the delay from a current delay to a new delay; recoupling the output of the adjustable delay; recoupling the input of the adjustable delay to receive the input clock signal; while the input of the adjustable delay is decoupled, tracking an edge relationship of a reference clock signal and the input clock signal having a different clock frequency than the reference clock signal, the input clock signal provided to the adjustable delay and maintaining the edge relationship after recoupling the input and output of the adjustable delay; and latching data in response to the delayed clock signal having the new delay. - View Dependent Claims (17, 18, 19, 20)
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21. A method of operating a memory device, comprising:
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receiving a clock signal in a first clock domain; generating an internal clock signal in a second clock domain having a phase relationship relative to a clock edge of the clock signal in the first clock domain, the clock signal in the second clock domain having a higher frequency than the clock signal in the first clock domain; ceasing generation of the internal clock signal; adjusting the phase relationship between the clock signals in the first clock domain and the internal clock signal to a new phase relationship while generation of the clock signal in the second clock domain is ceased; generating the internal clock signal having the new phase relationship relative to the clock edge of the clock signal in the first clock domain; and latching data in response to the internal clock signal. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28)
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Specification