Fractional-type phase-locked loop circuit with compensation of phase errors
First Claim
1. A fractional-type phase-locked loop circuit for synthesizing an output signal by multiplying a frequency of a reference signal by a fractional conversion factor, the circuit including:
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, whereinthe means for compensating includes means for calculating an incremental value, indicative of an incremental phase error, according to the conversion factor and the modulation value, means for calculating a correction value accumulating the incremental value, and means for conditioning the control signal according to the correction value.
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Abstract
A fractional-type phase-locked loop circuit is proposed for synthesizing an output signal multiplying a frequency of a reference signal by a fractional conversion factor, the circuit including means for generating a modulation value, means for generating a feedback signal dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on the average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio; in the circuit of an embodiment of the invention, the means for compensating includes means for calculating an incremental value, indicative of an incremental phase error, according to the conversion factor and the modulation value, means for calculating a correction value accumulating the incremental value, and means for conditioning the control signal according to the correction value.
27 Citations
18 Claims
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1. A fractional-type phase-locked loop circuit for synthesizing an output signal by multiplying a frequency of a reference signal by a fractional conversion factor, the circuit including:
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, wherein
the means for compensating includes means for calculating an incremental value, indicative of an incremental phase error, according to the conversion factor and the modulation value, means for calculating a correction value accumulating the incremental value, and means for conditioning the control signal according to the correction value. - View Dependent Claims (4, 5, 6, 7, 8, 9)
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, wherein
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2. A fractional-type phase-locked loop circuit for synthesizing an output signal by multiplying a frequency of a reference signal by a fractional conversion factor, the circuit including:
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, wherein
the means for compensating includes means for calculating an incremental value, indicative of an incremental phase error, according to the conversion factor and the modulation value, means for calculating a correction value accumulating the incremental value, and means for conditioning the control signal according to the correction value, and wherein the means for generating the modulation value includes a sigma-delta modulator having an order at least equal to two.
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, wherein
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3. A fractional-type phase-locked loop circuit for synthesizing an output signal by multiplying a frequency of a reference signal by a fractional conversion factor, the circuit including:
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, wherein
the means for compensating includes means for calculating an incremental value, indicative of an incremental phase error, according to the conversion factor and the modulation value, and means for calculating a correction value accumulating the incremental value, and means for conditioning the control signal according to the correction value, and wherein the means for generating the modulation value includes a multi-bit modulator.
- means for generating a modulation value, means for generating a feedback signal by dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on an average, means for generating a control signal indicative of a phase difference between the reference signal and the feedback signal, means for controlling the frequency of the output signal according to the control signal, and means for compensating a phase error caused by the modulation of the dividing ratio, wherein
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10. In a fractional-type phase-locked loop circuit, a method of synthesizing an output signal multiplying a frequency of a reference signal by a fractional conversion factor, the method including the steps of:
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generating a modulation value with a modulator, generating a feedback signal dividing the frequency of the output signal by a dividing ratio, the dividing ratio being modulated according to the modulation value for providing the conversion factor on the average, generating a control signal indicative of a phase difference between the reference signal and the feedback signal, controlling the frequency of the output signal according to the control signal, and compensating a phase error caused by the modulation of the dividing ratio, wherein the step of compensating includes; calculating an incremental value, indicative of an incremental phase error, according to the conversion factor and the modulation value, calculating a correction value accumulating the incremental value, and conditioning the control signal according to the correction value.
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11. A phase-locked loop, comprising:
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a phase-frequency detector operable to generate a phase-error signal based on a comparison of a reference signal and a feedback signal; a control circuit coupled to the phase-frequency detector and operable to generate a conditioning signal based on a modulation value and the feedback signal; and a generator coupled to the control circuit and the phase-frequency detector and operable to receive a control signal to generate an output signal, the control signal based on a summation of the phase-error signal and conditioning signal, wherein the control circuit comprises; a sigma-delta modulator operable to generate the modulation value a control logic block coupled to the sigma-delta modulator and operable to generate a correction value based on the modulation value and an adjusting value, the control logic block clocked by the feedback signal; and a digital-to-analog converter coupled to the control logic block operable to generate the conditioning signal based on the correction value. - View Dependent Claims (12, 13)
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14. A phase-locked loop, comprising:
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a phase-frequency detector operable to generate a phase-error signal based on a comparison of a reference signal and a feedback signal; a control circuit coupled to the phase-frequency detector and operable to generate a conditioning signal based on a modulation value and the feedback signal; and a generator coupled to the control circuit and the phase-frequency detector and operable to receive a control signal to generate an output signal, the control signal based on a summation of the phase-error signal and conditioning signal; wherein the control circuit comprises; a sigma-delta modulator operable to generate the modulation value; a control logic block coupled to the sigma-delta modulator and operable to generate a correction value based on the modulation value and an adjusting value, the control logic block clocked by the feedback signal; a digital-to-analog converter coupled to the control logic block operable to generate the conditioning signal based on the correction value; and wherein the sigma-delta generator comprises a first modifier operable to convert a first data set corresponding to the adjusting value into a second data set. - View Dependent Claims (15)
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16. A method for controlling the output of a phase-locked loop, the method comprising:
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determining a phase difference between a reference signal and a feedback signal with a phase frequency detector; generating a phase-error signal from the determined phase difference; generating a conditioning signal based upon a modulation value and the feedback signal; modifying the phase-error signal with the conditioning signal; and generating an output signal with a generator from the modified phase-error signal; wherein generating the conditioning signal comprises; generating a first data set based on an adjusting value generating a second data set based on a the first set of data and modulation value; and generating the conditioning signal based on the second data set. - View Dependent Claims (17, 18)
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Specification