Claims
- 1. A method comprising:
correcting for skew between a first clock signal and a second clock signal in response to selecting a first phase-locked loop circuit feedback path; and introducing a desired degree of skew between the first clock signal and the second clock signal in response to selecting a second phase-locked loop circuit feedback path.
- 2. The method of claim 1, wherein said introducing said desired degree of skew comprises overcorrecting for a delay in a circuit path between the first clock signal and the second clock signal.
- 3. The method of claim 1, wherein said introducing said desired degree of skew comprises adding one or more additional delay-inducing elements in the second phase-locked loop feedback path.
- 4. Apparatus comprising:
an input node operative to receive a first clock signal; an output node operative to receive a second clock signal; a phase-locked loop circuit including a first feedback path and a second feedback path, each of said feedback paths operative to introduce a different degree of skew between the first clock signal and the second clock signal; and a feedback path selector operative to select one of said feedback paths.
- 5. The apparatus of claim 4, wherein the first feedback path is operative to introduce substantially no skew between the first and second clock signals when selected.
- 6. The apparatus of claim 4, wherein the second feedback path is operative to introduce a desired degree of skew between the first and second clock signals when selected.
- 7. The apparatus of claim 4, further comprising a clock signal path between the input node and the output node, the clock signal path comprising a first delay-inducing element,
wherein the second feedback path comprises said first delay-inducing element and one or more additional delay-inducing elements operative to overcorrect for a skew between said input signal and said output signal caused by the first delay-inducing element.
- 8. The apparatus of claim 7, wherein said first delay-inducing element comprises a clock tree.
- 9. The apparatus of claim 7, wherein said one or more additional delay-inducing elements comprise a plurality of buffers.
- 10. The apparatus of claim 9, further comprising:
a phase-locked loop (PLL) including a PLL input node; and a first buffer between the input node and the PLL input node, wherein said first feedback path comprises a first delay-inducing element and a second delay-inducing element operative to provide a delay sufficient to correct for a delay introduced by the first buffer in the output signal.
- 11. Apparatus comprising:
an input node operative to receive an input signal; an output node operative to receive an output signal; a clock signal path between the input node and the output node, said clock signal path including a clock tree; a phase-locked loop circuit including
a first feedback path including the clock tree, a second feedback path including a string of buffers, and a mode selector operative to select the first feedback path in a first operating mode and to select the second feedback path in a second operating mode.
- 12. The apparatus of claim 11, wherein the first operating mode has a clocking scheme requiring substantially no skew between said input and output signals, and
wherein the second operating mode has a clocking scheme requiring a degree of skew between said input and output signals.
- 13. The apparatus of claim 11, wherein the second feedback path includes the clock tree.
- 14. The apparatus of claim 11, wherein the phase-locked loop (PLL) circuit includes a PLL input node, and further comprising a delay-inducing element between the input node and the PLL input node.
- 15. The apparatus of claim 14, wherein the first feedback path further comprises a second delay-inducing element operative to introduce a delay sufficient to correct for a delay between the input node and the PLL input node caused by the first delay-inducing element.
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to U.S. Provisional Patent Application Serial No. 60/340,544, filed on Dec. 12, 2001
Provisional Applications (1)
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Number |
Date |
Country |
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60340544 |
Dec 2001 |
US |