Lock detector and method of detecting lock status for phase lock loop
First Claim
1. A lock detector for a Phase Lock Loop (PLL) circuit comprising:
- a first signal counting circuit configured to define a plurality of observation periods according to a first oscillating signal and a predetermined cycle value;
a second signal counting circuit configured to determine a maximum counter value according to a second oscillating signal within each of the observation periods, the second oscillating signal being generated in relation to the first oscillating signal;
a comparator configured to determine, for each of the observation periods, whether the maximum counter value equals the predetermined cycle value; and
a lock status unit configured to generate a lock signal based on the maximum counter value being equal to the predetermined cycle value for a predetermined number of consecutive ones of the observation periods.
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Accused Products
Abstract
A lock detector for a PLL circuit includes a first signal counting circuit, a second signal counting circuit, a comparator, and a lock status unit. The first signal counting circuit is configured to define a plurality of observation periods according to a first oscillating signal and a predetermined cycle value. The second signal counting circuit is configured to determine a maximum counter value according to a second oscillating signal within each of the observation periods, and the second oscillating signal is generated in relation to the first oscillating signal. The comparator is configured to determine, for each of the observation periods, whether the maximum counter value equals the predetermined cycle value. The lock status unit is configured to generate a lock signal based on the maximum counter value being equal to the predetermined cycle value for a predetermined number of consecutive ones of the observation periods.
26 Citations
20 Claims
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1. A lock detector for a Phase Lock Loop (PLL) circuit comprising:
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a first signal counting circuit configured to define a plurality of observation periods according to a first oscillating signal and a predetermined cycle value; a second signal counting circuit configured to determine a maximum counter value according to a second oscillating signal within each of the observation periods, the second oscillating signal being generated in relation to the first oscillating signal; a comparator configured to determine, for each of the observation periods, whether the maximum counter value equals the predetermined cycle value; and a lock status unit configured to generate a lock signal based on the maximum counter value being equal to the predetermined cycle value for a predetermined number of consecutive ones of the observation periods. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A lock detector for a Phase Lock Loop (PLL) circuit comprising:
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a lock signal generator configured to generate a lock signal according to a relationship between a first maximum value and a second maximum value; a first counter configured to generate a counter value in response to a first oscillating signal; a first maximum detector coupled between the first counter and the lock signal generator and configured to determine the first maximum value of the counter value from the first counter; a second counter configured to generate a counter value in response to a second oscillating signal generated in relation to the first oscillating signal; and a second maximum detector coupled between the second counter and the lock signal generator and configured to determine the second maximum value of the counter value from the second counter. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A method of detecting a lock status of a Phase Lock Loop (PLL) circuit, the method comprising:
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generating a first maximum value by performing a counting operation based on a first oscillating signal; generating a second maximum value by performing a counting operation based on a second oscillating signal generated by the PLL circuit relative to the first oscillating signal; generating an equal event or an unequal event by comparing the first maximum value and the second maximum value; generating an equal event counter value, by a counter, in response to the equal event; and generating a lock signal after the equal event counter value equals a predetermined counter threshold value. - View Dependent Claims (17, 18, 19, 20)
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Specification