In-loop duty corrector delay-locked loop for multiphase clock generation
First Claim
Patent Images
1. A delay-locked loop (DLL) including:
- a plurality of serially-connected delay cells, wherein each delay cell includes an internal duty cycle correction loop;
delay correction circuitry for providing a control voltage to the plurality of delay cells via a DLL feedback loop; and
a lock detector that activates the duty cycle correction loop of each delay cell based on the control voltage.
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Abstract
A delay-locked loop (DLL) employs an in-loop duty cycle corrector (DCC) to provide accurate multiphase clock generation with 50% duty cycle. Each delay cell can advantageously provide both delay and duty cycle correction functionality. In one embodiment, delay correction can precede duty cycle correction. The bandwidths of the DCC and the DLL can differ by a factor of a decade to achieve fast and stable operation.
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Citations
26 Claims
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1. A delay-locked loop (DLL) including:
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a plurality of serially-connected delay cells, wherein each delay cell includes an internal duty cycle correction loop;
delay correction circuitry for providing a control voltage to the plurality of delay cells via a DLL feedback loop; and
a lock detector that activates the duty cycle correction loop of each delay cell based on the control voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 19)
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13. A delay cell for a delay-locked loop (DLL), the delay cell including:
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means for delaying an input signal to the delay cell based on a DLL feedback loop; and
means for modifying a duty cycle of an output signal of the delay cell based on an internal loop of the delay cell.
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14. A delay cell for a delay-locked loop (DLL), the delay cell including:
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a first transconductor that delays an input signal to the delay cell based on a DLL feedback loop; and
a duty cycle correction circuit for modifying a duty cycle of an output signal of the delay cell based on an internal loop of the delay cell. - View Dependent Claims (15, 16, 17, 18, 20, 21)
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22. A method of generating multiple phases of a clock in a delay-locked loop (DLL), the method comprising:
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using a plurality of delay cells to delay a clock received by the DLL, each delay cell outputting one phase of the clock;
performing delay correction using a DLL feedback loop, the DLL feedback loop connected to each delay cell; and
performing duty cycle correction within each delay cell of the DLL, thereby minimizing duty cycle offset propagation in the DLL. - View Dependent Claims (23, 24, 25, 26)
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Specification