Calibration techniques for frequency synthesizers
First Claim
1. A method of calibrating an oscillator comprising:
- using a frequency divider to divide the frequency of an oscillator signal to generate a first signal;
using a frequency divider to divide the frequency of a reference signal to generate a second signal;
wherein generating the first signal and generating the second signal comprise synchronizing the phases of the first and second signals during calibration; and
adjusting the frequency of the oscillator based on a comparison of the first and second signals, the adjusting comprising decreasing the oscillator frequency when the first signal edge arrives before the second signal edge, and increasing the oscillator frequency when the first signal edge arrives after the second signal edge.
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Accused Products
Abstract
In one embodiment, this disclosure describes a frequency synthesizer for use in a wireless communication device, or similar device that requires precision frequency synthesis but small amounts of noise. In particular, the frequency synthesizer may include a phase locked loop (PLL) and an integrated voltage controlled oscillator (VCO). The frequency synthesizer may implement one or more calibration techniques to quickly and precisely calibrate the VCO. In this manner, the analog gain of the VCO can be significantly reduced, which may improve performance of the wireless communication device. Also, the initial state of the PLL may be improved to reduce lock time of the PLL, which may enhance performance of the wireless communication device.
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Citations
61 Claims
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1. A method of calibrating an oscillator comprising:
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using a frequency divider to divide the frequency of an oscillator signal to generate a first signal; using a frequency divider to divide the frequency of a reference signal to generate a second signal;
wherein generating the first signal and generating the second signal comprise synchronizing the phases of the first and second signals during calibration; andadjusting the frequency of the oscillator based on a comparison of the first and second signals, the adjusting comprising decreasing the oscillator frequency when the first signal edge arrives before the second signal edge, and increasing the oscillator frequency when the first signal edge arrives after the second signal edge. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An apparatus comprising:
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circuitry that divides the frequency of an oscillator signal to generate a first signal; circuitry that divides the frequency of a reference signal to generate a second signal; circuitry that synchronizes the phase of the first signal with the phase of the second signal during calibration; and circuitry that adjusts the frequency of the oscillator based on a comparison of the first and second signals, the circuitry decreasing the oscillator frequency when the first signal edge arrives before the second signal edge, and the circuitry increasing the oscillator frequency when the first signal edge arrives after the second signal edge. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method of calibrating a frequency synthesizer comprising:
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receiving a first divided signal from a first circuitry, the first circuitry configured to divide the frequency of an oscillator signal to generate a first circuitry signal; receiving a second divided signal from a second circuitry, the second circuitry configured to divide the frequency of a reference signal to generate a second circuitry signal; initializing the first and second circuitry at the same time during calibration; and
generating a calibration signal based on a frequency difference between the first circuitry signal and second circuitry signal, the calibration signal decreasing the oscillator frequency when the first circuitry signal edge arrives before the second circuitry signal edge, and the calibration signal increasing the oscillator frequency when the first circuitry signal edge arrives after the second circuitry signal edge. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. An apparatus comprising:
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circuitry that divides the frequency of an oscillator signal to generate a first signal; circuitry that divides the frequency of a reference signal to generate a second signal, the reference signal being an externally generated temperature-compensated crystal oscillator signal; circuitry that synchronizes the phase of the first signal with the phase of the second signal during calibration; and circuitry that adjusts the frequency of the oscillator based on a comparison of the first and second signals, the circuitry increasing the oscillator frequency when the first signal edge arrives before the second signal edge, and the circuitry decreasing the oscillator frequency when the first signal edge arrives after the second signal edge. - View Dependent Claims (39, 40, 41, 42, 43)
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44. In a receiver for a wireless communication device, an apparatus comprising:
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circuitry that divides the frequency of an oscillator signal to generate a first signal; circuitry that divides the frequency of a reference signal to generate a second signal, the reference signal being an externally generated temperature-compensated crystal oscillator signal; circuitry that synchronizes the phase of the first signal with the phase of the second signal during calibration; and circuitry that adjusts the frequency of the oscillator based on a comparison of the first and second signals, the circuitry increasing the oscillator frequency when the first signal edge arrives before the second signal edge, and the circuitry decreasing the oscillator frequency when the first signal edge arrives after the second signal edge. - View Dependent Claims (45, 46, 47, 48, 49)
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50. In a transmitter for a wireless communication device, an apparatus comprising:
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circuitry that divides the frequency of an oscillator signal to generate a first signal; circuitry that divides the frequency of a reference signal to generate a second signal, the reference signal being an externally generated temperature-compensated crystal oscillator signal; circuitry that synchronizes the phase of the first signal with the phase of the second signal during calibration; and circuitry that adjusts the frequency of the oscillator based on a comparison of the first and second signals, the circuitry increasing the oscillator frequency when the first signal edge arrives before the second signal edge, and the circuitry decreasing the oscillator frequency when the first signal edge arrives after the second signal edge. - View Dependent Claims (51, 52, 53, 54, 55)
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56. An integrated circuit comprising:
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an oscillator comprising a plurality of switched capacitors for adjusting the frequency of the oscillator; circuitry that divides the frequency of the oscillator signal to generate a first signal; circuitry that divides the frequency of an externally generated temperature-compensated crystal oscillator signal to generate a second signal; circuitry that synchronizes the phase of the first signal with the phase of the second signal during calibration; and circuitry that adjusts the frequency of the oscillator based on a comparison of the first and second signals, the circuitry increasing the oscillator frequency when the first signal edge arrives before the second signal edge, and the circuitry decreasing the oscillator frequency when the first signal edge arrives after the second signal edge. - View Dependent Claims (57, 58, 59, 60, 61)
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Specification