Clock data recovery circuit capable of generating clock signal synchronized with data signal
First Claim
1. A clock data recovery circuit generating an output clock synchronized with a data signal, comprising:
- a first detection portion detecting a phase difference between said data signal and said output clock;
a variable delay portion varying a delay of a clock in accordance with a control code; and
a code changing portion changing a value of said control code,said code changing portion including;
a second detection portion detecting a value of a control code corresponding to a delay equal to one period of said output clock,a storage portion storing the value of the control code detected by said second detection portion, andan operation portion adding or subtracting at a time the value stored in said storage portion to/from the control code when a delay amount of said variable delay portion exceeds one period of the clock in synchronizing said output clock with said data signal while changing said control code in accordance with a detection result by said first detection portion.
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Accused Products
Abstract
A phase comparison circuit detects a phase difference between a data signal and the output from a variable delay circuit. A Code Operator detects a value of a control code corresponding to a delay equal to one period of an output clock. Then, when a delay amount of the variable delay circuit exceeds one period of a clock during synchronization of the output clock with the data signal while the control code is changed in accordance with the detection result by the phase delay circuit, a control code corresponding to a delay equal to one period of the output clock is added or subtracted to/from the control code at a time. Therefore, even if there is a difference in frequency between a data signal and a clock, it becomes possible to synchronize the data signal and the clock with application of the same clock phase.
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Citations
11 Claims
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1. A clock data recovery circuit generating an output clock synchronized with a data signal, comprising:
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a first detection portion detecting a phase difference between said data signal and said output clock; a variable delay portion varying a delay of a clock in accordance with a control code; and a code changing portion changing a value of said control code, said code changing portion including; a second detection portion detecting a value of a control code corresponding to a delay equal to one period of said output clock, a storage portion storing the value of the control code detected by said second detection portion, and an operation portion adding or subtracting at a time the value stored in said storage portion to/from the control code when a delay amount of said variable delay portion exceeds one period of the clock in synchronizing said output clock with said data signal while changing said control code in accordance with a detection result by said first detection portion. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification