Phase locked loop with self-calibration
First Claim
1. A method for self-calibrating a phase locked loop (PLL), comprising:
- setting a frequency range setting of a voltage controlled oscillator (VCO) to a series of sequential digital values for a series of respective sequential output frequencies, including setting the frequency range to a first digital value for a first output frequency, wherein in an initial setting of the frequency range to a first digital value the first digital value is set to 2(N-1), N being a number of bits of the frequency range setting, wherein N is at least three;
measuring a first difference between a reference frequency and a feedback frequency resulting from the first output frequency;
calculating an inverted digital value of the first digital;
setting the frequency range setting to the inverted digital value of the first digital value calculated in the calculating step as the next digital value in the series of sequential digital values for a second output frequency;
measuring a second difference between the reference frequency and the feedback frequency resulting from the second output frequency; and
selecting a value of the frequency range setting based at least in part on the first difference and the second difference.
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Abstract
A method for self-calibrating a phase locked loop (PLL) includes setting a frequency range setting of a voltage controlled oscillator (VCO) to a first digital value for a first output frequency. A first difference is measured between a reference frequency and a feedback frequency resulting from the first output frequency. The frequency range setting is set to an inverted digital value of the first digital value for a second output frequency. A second difference is measured between the reference frequency and the feedback frequency resulting from the second output frequency. A value of the frequency range setting is selected based on the first difference and the second difference.
25 Citations
19 Claims
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1. A method for self-calibrating a phase locked loop (PLL), comprising:
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setting a frequency range setting of a voltage controlled oscillator (VCO) to a series of sequential digital values for a series of respective sequential output frequencies, including setting the frequency range to a first digital value for a first output frequency, wherein in an initial setting of the frequency range to a first digital value the first digital value is set to 2(N-1), N being a number of bits of the frequency range setting, wherein N is at least three; measuring a first difference between a reference frequency and a feedback frequency resulting from the first output frequency; calculating an inverted digital value of the first digital; setting the frequency range setting to the inverted digital value of the first digital value calculated in the calculating step as the next digital value in the series of sequential digital values for a second output frequency; measuring a second difference between the reference frequency and the feedback frequency resulting from the second output frequency; and selecting a value of the frequency range setting based at least in part on the first difference and the second difference. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A phase locked loop (PLL) with self-calibration, comprising:
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a voltage controlled oscillator (VCO); and a controller module adapted to; set a frequency range setting of the VCO to a series of sequential digital values for a series of respective sequential output frequencies, including a first digital value for a first output frequency, wherein in an initial value of the first digital value is 2(N-1), N being a number of bits of the frequency range setting, wherein N is at least three; measure a first difference between a reference frequency and a feedback frequency resulting from the first output frequency; set the frequency range setting to an inverted digital value of the first digital value for a second output frequency as the next digital value in the series of sequential digital values; measure a second difference between the reference frequency and the feedback frequency resulting from the second output frequency; and select a value of the frequency range setting based on the first difference and the second difference. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. An integrated circuit having a phase locked loop (PLL) comprising:
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a voltage controlled oscillator (VCO) controller for setting a frequency range setting of a voltage controlled oscillator (VCO) to a series of sequential digital values for a series of respective sequential output frequencies, there being more than four output frequencies in the series of respective sequential output frequencies, including a first digital value for a first output frequency and setting the frequency range setting to an inverted digital value of the first digital value for a second output frequency as the next digital value in the series of sequential digital values, an initial value of the first output frequency being a middle output frequency in the series of respective sequential output frequencies; and a PLL controller for measuring a first difference between a reference frequency and a feedback frequency resulting from the first output frequency, measuring a second difference between the reference frequency and the feedback frequency resulting from the second output frequency, and deciding whether a target frequency is between the first output frequency and the second output frequency; wherein the VCO controller is configured to change the first digital value of the frequency range setting if the target frequency is not between the first output frequency and the second output frequency, and to select a value of the frequency range setting based on the first difference and the second difference.
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Specification