Automatic frequency calibration apparatus and method for a phase-locked loop based frequency synthesizer
First Claim
1. An automatic frequency calibration apparatus for a phase-locked loop based frequency synthesizer, the apparatus comprising:
- a frequency-to-digital converter configured to count directly a frequency of a VCO output signal from a VCO and convert the frequency of the VCO output signal into a first digital value;
a target value setting section configured to output a second digital value corresponding to a target frequency; and
a finite state machine configured to calibrate the frequency of the VCO output signal by using a difference of the first digital value and the second digital value,wherein the frequency-to-digital converter includes;
a frequency divider configured to divide the frequency of the VCO output signal with a given dividing ratio, convert the divided signals into multiple phase signals having multiple phases, and output the multiple phase signals;
at least one counter configured to count at least one of the multiple phase signals; and
an adder configured to add the counted results by the at least one counter.
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Abstract
An automatic frequency calibration apparatus and a method thereof for a phase-locked loop based frequency synthesizer are disclosed. The apparatus includes a frequency-to-digital converter configured to convert a frequency of a VCO output signal to a first digital value, a target value setting section configured to provide a second digital value corresponding to a target frequency, and a finite state machine configured to calibrate the frequency of the VCO output signal by using the difference of the first digital value and the second digital value. Accordingly, the calibration speed and a frequency resolution of the automatic frequency calibration apparatus in a frequency synthesizer may be enhanced.
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Citations
12 Claims
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1. An automatic frequency calibration apparatus for a phase-locked loop based frequency synthesizer, the apparatus comprising:
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a frequency-to-digital converter configured to count directly a frequency of a VCO output signal from a VCO and convert the frequency of the VCO output signal into a first digital value; a target value setting section configured to output a second digital value corresponding to a target frequency; and a finite state machine configured to calibrate the frequency of the VCO output signal by using a difference of the first digital value and the second digital value, wherein the frequency-to-digital converter includes; a frequency divider configured to divide the frequency of the VCO output signal with a given dividing ratio, convert the divided signals into multiple phase signals having multiple phases, and output the multiple phase signals; at least one counter configured to count at least one of the multiple phase signals; and an adder configured to add the counted results by the at least one counter. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An automatic frequency calibration apparatus for a fractional-N frequency synthesizer based on a phase-locked loop, the apparatus comprising:
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a frequency divider configured to divide a frequency of VCO output signal with a given dividing ratio, convert the divided signals into multiple phase signals having multiple phases, and output the multiple phase signals; and at least one counter configured to count at least one of the multiple phase signals; and an adder configured to add the counted results, wherein the counted results are identical to a value obtained by counting directly the VCO output signal, a frequency of the VCO output signal is converted into a first digital value through the counter, the first digital value is compared with a second digital value corresponding to a target frequency, and the frequency of the VCO output signal is calibrated in accordance with the compared result.
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12. An automatic frequency calibration method for a phase-locked loop based fractional-N frequency synthesizer, the method comprising:
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counting directly a frequency of a VCO output signal; and comparing a first digital value in accordance with the counted result with a second digital value corresponding to a target frequency, and calibrating the frequency of the VCO output signal in accordance with the compared result, wherein the counting procedure includes; dividing the VCO output signal with a given dividing ratio; converting the divided signals into multiple signals having multiple phases; and counting the multiple phase signals and then adding the counted results.
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Specification