Cycle slip detector and phase locked loop circuit and digital signal reproducing apparatus using the same
First Claim
1. A cycle slip detector for detecting a cycle slip in a phase error signal, comprising:
- first determining means for determining that the value of said phase error signal being supplied thereto is larger than a first threshold value near a maximum value possibly taken by said phase error signal to generate a first determining signal;
second determining means for determining that the value of said phase error signal being supplied thereto is smaller than a second threshold value near a minimum value possibly taken by said phase errors to generate a second determining signal; and
detecting signal generating means for generating a cycle slip detecting signal when said first determining signal and said second determining signal are generated in succession.
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Accused Products
Abstract
A cycle slip detector of the invention has first and second comparators. The first comparator determines that the value of a phase error signal being supplied thereto is larger than a first threshold value near a maximum value possibly taken by the phase error signal, and responsively generates a first determining signal. The second comparator determines that the value of the phase error signal being supplied thereto is smaller than a second threshold value of a minimum value possibly taken by the phase error signal, and responsively generates a second determining signal. The cycle slip detector generates a cycle slip detecting signal when the first determining signal and the second determining signal generate in succession. By applying the cycle slip detector as mentioned, it is possible to provide a phase locked loop circuit having a wide frequency range in which a withdraw or pull-in operation is permitted. If the cycle slip detector is applied to a digital signal reproducing apparatus, it is possible to reduce an access time required to read a signal at a specified recording position on an recording medium from the unlock state of the phase locked loop circuit.
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Citations
10 Claims
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1. A cycle slip detector for detecting a cycle slip in a phase error signal, comprising:
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first determining means for determining that the value of said phase error signal being supplied thereto is larger than a first threshold value near a maximum value possibly taken by said phase error signal to generate a first determining signal; second determining means for determining that the value of said phase error signal being supplied thereto is smaller than a second threshold value near a minimum value possibly taken by said phase errors to generate a second determining signal; and detecting signal generating means for generating a cycle slip detecting signal when said first determining signal and said second determining signal are generated in succession. - View Dependent Claims (2)
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3. A phase locked loop circuit for generating a phase synchronizing signal synchronized in phase to an input signal, comprising:
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error detecting means for detecting a phase error in said input signal and for generating a phase error signal in accordance the detected phase error; a cycle slip detector including first determining means for determining that the value of said phase error signal being supplied thereto is larger than a first threshold value near a maximum value possibly taken by said phase error signal to generate a first determining signal;
second determining means for determining that the value of said phase error signal being supplied thereto is smaller than a second threshold value near a minimum value possibly taken by said phase error signal to generate a second determining signal; and
detecting signal generating means for generating a cycle slip detecting signal when said first determining signal and said second determining signal are generated in succession;an adding means for adding said phase error signal and said cycle slip detecting signal to generate a sum signal in accordance with an addition value of both said signals; a loop filter for passing a low frequency component of said sum signal therethrough; and
oscillating means for generating said phase synchronizing signal having an oscillating frequency and a phase in accordance with said low frequency component. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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10. A digital signal reproducing apparatus for reproducing a digital signal from a read signal acquired by reading a recording medium, comprising:
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digitizing means for converting said reading signal to a digital form using a sampling timing signal and for outputting a digital signal; error detecting means for detecting a phase error in sampling timing of said digitizing means relative to said read signal to generate a phase error signal in accordance with said phase error; a cycle slip detector including first determining means for determining that the value of said phase error signal being supplied thereto is larger than a first threshold value near a maximum value possibly taken by said phase error signal to generate a first determining signal;
second determining means for determining that the value of said phase error signal being supplied thereto is smaller than a second threshold value near a minimum value possibly taken by said phase error signal to generate a second determining signal; and
detecting signal generating means for generating a cycle slip detecting signal when said first determining signal and said second determining signal are generated in succession;adding means for adding said phase error signal and said cycle slip detecting signal to generate a sum signal in accordance with an addition value of both said signals; a loop filter for passing a low frequency component of said sum signal therethrough; oscillating means for generating said sampling timing signal having an oscillating frequency and a phase in accordance with said low frequency component; and decoding means for decoding said digital signal.
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Specification