Circuit and method for operating a delay-lock loop in a power saving manner
First Claim
1. A method of operating a delay-lock loop included in a memory device, the method comprising:
- in a normal operating mode of the memory device, continuously coupling a reference clock signal to a delay line used in the delay-lock loop; and
in a standby mode of the memory device;
entering a standby period in which the reference clock signal is isolated from the delay line; and
while in the standby period, periodically coupling the reference clock signal to the delay line for an update period of sufficient duration to allow the delay-lock loop to achieve a locked condition, and then re-entering the standby period.
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Accused Products
Abstract
A control circuit for a delay-lock loop having a delay line and a phase detector is used in a memory device. In a standby mode, the control circuit isolates a reference clock signal from the delay-lock loop to save power unless a clock signal generated by the loop is needed for a memory operation. However, the reference signal is periodically coupled to the delay line for a sufficient period to achieve a locked condition. As a result, the phase of the output signal from delay-lock loop can be quickly locked to the phase of the reference signal when a memory operation is to occur during a normal operating mode. When transitioning between the standby mode and the normal operating mode, the control circuit couples the reference clock signal to the delay line for at least a predetermined period of time.
33 Citations
32 Claims
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1. A method of operating a delay-lock loop included in a memory device, the method comprising:
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in a normal operating mode of the memory device, continuously coupling a reference clock signal to a delay line used in the delay-lock loop; and
in a standby mode of the memory device;
entering a standby period in which the reference clock signal is isolated from the delay line; and
while in the standby period, periodically coupling the reference clock signal to the delay line for an update period of sufficient duration to allow the delay-lock loop to achieve a locked condition, and then re-entering the standby period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of operating a delay-lock loop included in a memory device, the method comprising:
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in a standby mode of the memory device, isolating the reference clock signal from a delay line used in the delay-lock loop; and
in a normal operating mode of the memory device, continuously coupling the reference clock signal to the delay line for at least a predetermined period regardless of whether or not the memory device remains in the normal operating mode. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. In a memory device having a delay-lock loop including a delay line, a method of transitioning the memory device from a normal operating mode in which a reference clock signal is coupled to the delay line to a standby mode in which the reference clock signal is isolated from the delay line, the method comprising:
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determining if the delay-lock loop is in a locked condition when entering the standby mode;
if the determination is made that the delay-lock loop is in a locked condition when entering the standby mode, immediately isolating the reference clock signal from the delay line; and
if the determination is made that the delay-lock loop is not in a locked condition when entering the standby mode, continuing to couple the reference clock signal to the delay line for a predetermined period before isolating the reference clock signal from the delay line. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31)
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32-59. -59. (canceled)
Specification