Apparatus and method for reflection delay splitting digital clock distribution
First Claim
Patent Images
1. A method of distributing a clock signal over a transmission line, the method comprising:
- providing a return line geometrically matched to the transmission line;
generating an output clock signal onto a transmission line;
detecting a returned clock signal on the return line;
detecting a first phase difference between a reference clock signal and the output clock signal;
detecting a second phase difference between the reference clock signal and the returned clock signal;
controlling the phase of the output clock signal based on an average of the first and second phase differences.
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Abstract
A clock distribution system including a first and second phase detector. The first phase detector outputs a phase lead of an output clock signal. The second phase detector outputs a phase lag of a returned clock signal. Circuitry is included that propagates the output clock signal onto a transmission line based on the average the output of the first phase detector and the second phase detector.
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Citations
12 Claims
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1. A method of distributing a clock signal over a transmission line, the method comprising:
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providing a return line geometrically matched to the transmission line; generating an output clock signal onto a transmission line; detecting a returned clock signal on the return line; detecting a first phase difference between a reference clock signal and the output clock signal; detecting a second phase difference between the reference clock signal and the returned clock signal; controlling the phase of the output clock signal based on an average of the first and second phase differences. - View Dependent Claims (4, 5)
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2. A method of distributing a clock signal, the method comprising:
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generating an output clock signal onto a transmission line; detecting a returned clock signal by sensing a reflection of the output clock signal on the transmission line; detecting a first phase difference between a reference clock signal and the output clock signal; detecting a second phase difference between the reference clock signal and the returned clock signal; controlling the phase of the output clock signal based on an average of the first and second phase differences. - View Dependent Claims (3)
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6. A method of distributing a clock signal, the method comprising:
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generating an output clock signal onto a transmission line; detecting a returned clock signal; detecting a first phase difference between a reference clock signal and the output clock signal; detecting a second phase difference between the reference clock signal and the returned clock signal; controlling the phase of the output clock signal based on an average of the first and second phase differences by driving a voltage controlled oscillator using the average of the first and second phase differences; and buffering the output of the voltage controlled oscillator and providing a build out impedance to match the transmission line impedance.
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7. A clock distribution circuit comprising:
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a first phase detector that outputs a phase lead of an output clock signal; a second phase detector that outputs a phase lag of a returned clock signal; circuitry that propagates the output clock signal onto a transmission line based on the average the output of the first phase detector and the second phase detector; and circuitry to detect the returned clock signal as a reflected clock signal on the transmission line.
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8. A clock distribution circuit comprising:
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a first phase detector that outputs a phase lead of an output clock signal; a second phase detector that outputs a phase lag of a returned clock signal; circuitry that propagates the output clock signal onto a transmission line based on the average the output of the first phase detector and the second phase detector; and a signal return line separate from the transmission line, wherein the returned clock signal is sensed from the signal return line. - View Dependent Claims (9)
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10. A clock distribution system comprising:
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a referent ce clock that output a clock signal; a first clock distribution circuit comprising; a first phase detector that outputs a phase lead of a first output clock signal; a second phase detector that outputs a phase lag of a first returned clock signal; and first circuitry that propagates the first output clock signal onto a first transmission line based on the average the output of the first phase detector and the second phase detector; a second clock distribution circuit comprising; a third phase detector that outputs a phase lead of a second output clock signal; a fourth phase detector that outputs a phase lag of a second returned clock signal; and second circuitry that propagates the first output clock signal onto a second transmission line based on the average the output of the third phase detector and the fourth phase detector; and wherein the first transmission line is a different length than the second transmission line and the first and second output clock signals coincide at the end of the first and second transmission line.
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11. A method of distributing a reference clock signal, the method comprising:
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sensing an output clock signal to be sent over a transmission line; sensing a reflected clock signal at the beginning of the transmission line; and adjusting the output clock signal based on an average of a first phase difference between the output clock signal and the reference clock signal and a second phase difference between the reflected clock signal and the reference clock signal.
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12. A method of distributing a reference clock signal, the method comprising:
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sensing an output clock signal to be sent over a transmission line; sensing a returned clock signal at the end of a signal return line matched to the transmission line; and adjusting the output clock signal based on an average of a first phase difference between the output clock signal and the reference clock signal and a second phase difference between the returned clock signal and the reference clock signal.
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Specification