Oscillator tuning method
First Claim
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1. An apparatus comprising:
- a first circuit configured to generate an output signal oscillating at a first frequency in response to a first control signal; and
a second circuit configured to (a) receive a calibration signal oscillating at a second frequency and (b) generate said first control signal in response to (i) a counter value when in a first mode and (ii) a stored value when in a second mode, wherein, while in said first mode, said counter value is adjusted in response to a difference between said first frequency and said second frequency.
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Abstract
An apparatus comprising an output circuit and a control circuit. The output circuit may be configured to generate an output signal oscillating at a frequency in response to a control signal. The control circuit may be configured to generate the control signal in response to (i) a frequency of said input signal when in a first mode and (ii) a stored value when in a second mode.
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Citations
23 Claims
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1. An apparatus comprising:
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a first circuit configured to generate an output signal oscillating at a first frequency in response to a first control signal; and
a second circuit configured to (a) receive a calibration signal oscillating at a second frequency and (b) generate said first control signal in response to (i) a counter value when in a first mode and (ii) a stored value when in a second mode, wherein, while in said first mode, said counter value is adjusted in response to a difference between said first frequency and said second frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 21, 22, 23)
a phase detector configured to generate a detect signal in response to said calibration signal and said output signal.
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9. The apparatus according to claim 8, wherein said second circuit further comprises:
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a logic circuit configured to generate a plurality of second control signals in response to said input signal and said detect signal; and
a counter configured to generate said counter value in response to at least one of said plurality of second control signals.
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10. The apparatus according to claim 1, wherein said second circuit is configured to generate said first control signal such that said first frequency is a multiple of said second frequency.
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21. The apparatus according to claim 9, wherein said second circuit further comprises:
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a memory configured to (i) present said stored value and (ii) store said counter value in response to one of said plurality of second control signals; and
a multiplexer configured to select either said counter value or said stored value as said control signal in response to one of said plurality of second control signals.
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22. The apparatus according to claim 21, wherein said memory is non-volatile.
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23. The apparatus according to claim 1, wherein said counter value is frozen when said first frequency and said second frequency are substantially the same.
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11. An apparatus comprising:
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means for generating an output signal oscillating at a first frequency in response to a control signal; and
means for generating said control signal in response to (i) a counter value when in a first mode and (ii) a stored value when in a second mode, wherein, while in said first mode, said counter value is adjusted in response to a difference between said first frequency and a second frequency of a calibration signal.
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12. A method for tuning an oscillator, comprising the steps of:
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(A) detecting the presence of an input signal oscillating at a first frequency;
(B) generating an output signal oscillating at a second frequency in response to a control signal; and
(C) calibrating said control signal when said input signal is present in response to a counter value, wherein said counter value is adjusted in response to a difference between said first frequency and said second frequency. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
setting an initial value for said counter value.
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14. The method according to claim 13, wherein step (C) further comprises:
passing said initial value to a frequency generator.
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15. The method according to claim 12, wherein step (C) further comprises:
increasing said counter value when said first frequency of said input signal is greater than said second frequency of said output signal.
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16. The method according to claim 12, wherein step (C) further comprises:
decreasing said counter value when said first frequency of said input signal is less than said second frequency of said output signal.
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17. The method according to claim 12, wherein step (C) further comprises:
determining whether said first frequency of said input signal is substantially the same as said second frequency of said output signal.
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18. The method according to claim 12, wherein step (C) further comprises:
freezing said counter value when a phase of said input signal and a phase of said output signal are substantially the same.
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19. The method according to claim 18, wherein step (C) further comprises:
storing said counter value to a non-volatile memory.
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20. The method according to claim 19, wherein step (C) further comprises:
generating said control signal from said stored value.
Specification