Skew correction system eliminating phase ambiguity by using reference multiplication
First Claim
1. A method of generating a local clock signal, said method comprising:
- introducing a first periodic signal with a period TC into a first end of a signal transmission system for transmission over the signal transmission system from the first end to a second end;
introducing a second periodic signal with a period TC into the second end for transmission over the signal transmission system from the second end to the first end;
at a preselected location along the signal transmission system, detecting the first and second periodic signals, wherein the detected first and second periodic signals have associated skews;
based on both the detected first and second periodic signals, generating a third periodic signal that has a fixed skew that is between the skews of the detected first and second periodic signals;
generating a fourth periodic signal with a frequency of 1/TR;
dividing the frequency of the fourth periodic signal by 2N to generate a fifth periodic signal, wherein N is a number that is greater than 1;
phase locking the fifth periodic signal to the third periodic signal so that TR=TC; and
deriving the local clock signal from the fourth periodic signal, wherein the local clock signal has a frequency that is greater than the first and second periodic signals.
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Abstract
A system for generating a local clock signal, the system including: a skew correction circuit for receiving first and second periodic signals that have associated skews, wherein the skew correction circuit is configured to use the received first and second periodic signals to generate a third periodic signal that has a fixed skew between the skews of the first and second periodic signals; a phase detector with a first input that receives the third periodic signal from the skew correction circuit and a second input; a variable oscillator for generating an output signal having a frequency that is controlled by the phase detector; and a frequency divider for dividing the frequency of the oscillator'"'"'s output signal, wherein the frequency-divided output signal is fed back to the second input of the phase detector, and wherein the local clock signal is derived from the oscillator'"'"'s output signal.
38 Citations
29 Claims
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1. A method of generating a local clock signal, said method comprising:
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introducing a first periodic signal with a period TC into a first end of a signal transmission system for transmission over the signal transmission system from the first end to a second end;
introducing a second periodic signal with a period TC into the second end for transmission over the signal transmission system from the second end to the first end;
at a preselected location along the signal transmission system, detecting the first and second periodic signals, wherein the detected first and second periodic signals have associated skews;
based on both the detected first and second periodic signals, generating a third periodic signal that has a fixed skew that is between the skews of the detected first and second periodic signals;
generating a fourth periodic signal with a frequency of 1/TR;
dividing the frequency of the fourth periodic signal by 2N to generate a fifth periodic signal, wherein N is a number that is greater than 1;
phase locking the fifth periodic signal to the third periodic signal so that TR=TC; and
deriving the local clock signal from the fourth periodic signal, wherein the local clock signal has a frequency that is greater than the first and second periodic signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A system for generating a local clock signal, said system comprising:
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a skew correction circuit which has a first input for receiving a first periodic signal and a second input for receiving a second periodic signal, wherein the received first and second periodic signals have associated skews, wherein the skew correction circuit is configured to use both the received first and second periodic signals to generate a third periodic signal that has a fixed skew that is between the skews of the first and second periodic signals;
a phase detector with a first input that receives the third periodic signal from the skew correction circuit and a second input;
a variable oscillator for generating an output signal having a frequency that is controlled by the phase detector; and
a frequency divider which divides the frequency of the oscillator'"'"'s output signal to produce a frequency-divided output signal, wherein the frequency-divided output signal is fed back to the second input of the phase detector, and wherein the local clock signal is derived from the oscillator'"'"'s output signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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Specification