Half-speed clock recovery and demultiplexer circuit
First Claim
1. A clock recovery and demultiplexer circuit for recovering a clock signal from a received data signal and for demultiplexing the received data signal, and operating at a fraction of the data rate of the received data signal, said circuit comprising:
- a. clock signal generating means for generating a reference clock signal having a plurality of phases, said generated reference clock signal having a rate less than the data rate of the received data signal;
b. comparing means for comparing the phase angle between said generated reference clock signal and the received data signal;
c. frequency adjusting means responsive to said phase angle comparing means for adjusting said rate of said generated reference clock signal to synchronize said generated clock signal and the received data signal; and
d. demultiplexing means for demultiplexing the received data signal into parallel signals at data rates lower than the data rate of the received data signal using at least one of each of the phase of said generated reference clock signal and inverted phases of said generated reference clock signal.
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Accused Products
Abstract
A clock recovery circuit and demultiplexer circuit which operate at half the data rate of a received data stream. The half-speed clock recovery circuit generates a 0 and 90-degree clock at half the rate of the incoming data. These clocks are sampled by a pair of edge triggered flip-flops using the transitions of the received data as triggers. The outputs of these flip-flops are exclusive OR-ed to provide a signal indicating whether the generated clock leads or lags the received data. The half-speed 1:2 demultiplexer circuit uses the rising and falling edges of a half-speed 90-degree clock to latch the received data through a pair of flip-flops. The outputs of these flip-flops, each triggered by a different edge of the clock, make up two demultiplexed data streams. The clock recovery and demultiplexer circuits of the present invention can be extended to operate at lower clock rates and configured to provide wider demultiplexing.
149 Citations
11 Claims
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1. A clock recovery and demultiplexer circuit for recovering a clock signal from a received data signal and for demultiplexing the received data signal, and operating at a fraction of the data rate of the received data signal, said circuit comprising:
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a. clock signal generating means for generating a reference clock signal having a plurality of phases, said generated reference clock signal having a rate less than the data rate of the received data signal; b. comparing means for comparing the phase angle between said generated reference clock signal and the received data signal; c. frequency adjusting means responsive to said phase angle comparing means for adjusting said rate of said generated reference clock signal to synchronize said generated clock signal and the received data signal; and d. demultiplexing means for demultiplexing the received data signal into parallel signals at data rates lower than the data rate of the received data signal using at least one of each of the phase of said generated reference clock signal and inverted phases of said generated reference clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of recovering a clock signal from a received data signal and for demultiplexing the received data signal, comprising the steps of:
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a. generating a plurality of phases of a reference clock signal at a rate less than the data rate of the received data signal; b. comparing the phase angle between said generated reference clock signal and the received data stream; c. adjusting the frequency of said generated reference clock signal as a function of said comparing step to thereby synchronize said generated reference clock signal and the received data signal; and d. demultiplexing the received data signal into parallel signals at data rates lower than the data rate of the received data signal, using at lease one each of the phases of the generated reference clock signal and inverted phases of the generated reference clock signal. - View Dependent Claims (9, 10)
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11. A clock recovery and demultiplexer circuit for recovering clock signal from a received data signal and for demultiplexing the received data stream, and operating at a fraction of the data rate of the received data signal, said circuit comprising:
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a. an oscillator for generating a reference clock signal having a plurality of phases, said generated reference clock signal having a rate less than the data rate of the received data signal; b. a phase comparator for comparing the phase angle between said generated reference clock signal and the received data signal; c. a feedback loop for adjusting said rate of said generated reference clock signal to synchronize said generated clock signal and the received data stream in response to a lead-lag signal generated by said phase comparator; and a demultiplexer for demultiplexing the received data stream into parallel signals at data rates lower than the data rate of the received data stream using at least one of each of the phase of said generated reference clock signal and inverted phases of said generated reference clock signal.
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Specification