Modulation circuit and operating method thereof
First Claim
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1. A modulation circuit, comprising:
- a phase locked loop (PLL) circuit, for generating an output oscillating signal in response to a reference signal, a first control signal and a second control signal, the PLL circuit comprises;
a phase frequency detector, for detecting a phase difference between the reference signal and a divided signal;
a charge pump coupled to the phase frequency detector;
a loop filter, coupled to the charge pump, for outputting a filtered signal in response to the phase difference;
an oscillating module, for generating the output oscillating signal in response to the filtered signal and the first control signal, comprising;
a digital controlled capacitor bank, wherein the first control signal controls the capacitance of the digital controlled capacitor bank to adjust a frequency of the output oscillating signal; and
voltage tuning capacitor bank, for performing phase-locking in response to the filtered signal; and
the frequency divider, coupled to the oscillating module and the phase frequency detector, for dividing the frequency of the output oscillating signal by the divider value to generate the divided signal;
a scalar circuit, coupled to the PLL circuit, for receiving modulating data and generating the first control signal in response to the modulating data to control frequency deviation of the output oscillating signal, wherein the first control signal is in a digital form;
a sigma-delta modulator for receiving the same modulating data and generating the second control signal according to the modulating data to modulate a divider value of a frequency divider of the PLL circuit;
a phase quantizer, for quantizing the phase difference information between reference signal and divided signal to generate quantized phase difference information in digital format; and
a calibration circuit, coupled to the phase quantizer, for calibrating an estimated tuning gain of the oscillating module in response to the quantized phase difference information.
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Abstract
A modulation circuit includes a phase locked loop (PLL) circuit, a scalar circuit and a sigma-delta modulator. The PLL circuit is for generating an output oscillating signal in response to a reference signal, a first control signal and a second control signal. The scalar circuit is for generating the first control signal in response to modulating data to control frequency deviation of the output oscillating signal, wherein the first control signal is in a digital form. The sigma-delta modulator is for generating the second control signal according to the modulating data to modulate a divider value of a frequency divider of the PLL circuit.
20 Citations
19 Claims
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1. A modulation circuit, comprising:
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a phase locked loop (PLL) circuit, for generating an output oscillating signal in response to a reference signal, a first control signal and a second control signal, the PLL circuit comprises; a phase frequency detector, for detecting a phase difference between the reference signal and a divided signal; a charge pump coupled to the phase frequency detector; a loop filter, coupled to the charge pump, for outputting a filtered signal in response to the phase difference; an oscillating module, for generating the output oscillating signal in response to the filtered signal and the first control signal, comprising; a digital controlled capacitor bank, wherein the first control signal controls the capacitance of the digital controlled capacitor bank to adjust a frequency of the output oscillating signal; and voltage tuning capacitor bank, for performing phase-locking in response to the filtered signal; and the frequency divider, coupled to the oscillating module and the phase frequency detector, for dividing the frequency of the output oscillating signal by the divider value to generate the divided signal; a scalar circuit, coupled to the PLL circuit, for receiving modulating data and generating the first control signal in response to the modulating data to control frequency deviation of the output oscillating signal, wherein the first control signal is in a digital form; a sigma-delta modulator for receiving the same modulating data and generating the second control signal according to the modulating data to modulate a divider value of a frequency divider of the PLL circuit; a phase quantizer, for quantizing the phase difference information between reference signal and divided signal to generate quantized phase difference information in digital format; and a calibration circuit, coupled to the phase quantizer, for calibrating an estimated tuning gain of the oscillating module in response to the quantized phase difference information. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An operating method of a modulation circuit comprising a phase quantizer and a calibration circuit, comprising:
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generating, by a phase locked loop (PLL) circuit, an output oscillating signal in response to a reference signal, a first control signal and a second control signal, wherein the PLL circuit comprises a phase frequency detector, a charge pump, a loop filter, an oscillating module and the frequency divider; receiving modulating data and generating, by a scalar circuit coupled to the PLL circuit, the first control signal in response to the modulating data to control frequency deviation of the output oscillating signal, wherein the first control signal is in a digital form; receiving the same modulating data and generating, by a sigma-delta modulator coupled to the PLL circuit, the second control signal according to the modulating data to modulate a divider value of a frequency divider of the PLL circuit; detecting, by the phase frequency detector, a phase difference between the reference signal and a divided signal; outputting, by the loop filter, a filtered signal in response to the phase difference; generating, by the oscillating module, the output oscillating signal in response to the filtered signal and the first control signal; dividing, by the frequency divider, the frequency of the output oscillating signal by the divider value to generate the divided signal; wherein the oscillating module comprises a digital controlled capacitor bank and a voltage tuning capacitor bank, the first control signal controls the capacitance of the digital controlled capacitor bank to adjust a frequency of the output oscillating signal, and the voltage tuning capacitor bank performs phase-locking in response to the filtered signal; quantizing, by the phase quantizer, the phase difference information between reference signal and divided signal to generate quantized phase difference information in digital format; and calibrating, by the calibration circuit, an estimated tuning gain of the oscillating module in response to the quantized phase difference information. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. An operating method of a modulation circuit, comprising:
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generating, by a phase locked loop (PLL) circuit, an output oscillating signal in response to a reference signal, a first control signal and a second control signal; receiving modulating data and generating, by a scalar circuit coupled to the PLL circuit, the first control signal in response to the modulating data to control frequency deviation of the output oscillating signal, wherein the first control signal is in a digital form; receiving the same modulating data and generating, by a sigma-delta modulator coupled to the PLL circuit, the second control signal according to the modulating data to modulate a divider value of a frequency divider of the PLL circuit; applying a frequency step to the PLL circuit; quantizing phase difference information indicating a phase difference between the reference signal and the divided signal; accumulating the phase difference information during a first time interval and a second time interval to obtain a first accumulated result and a second accumulated result, respectively; and calibrating an estimated tuning gain for an oscillating module of the PLL circuit according to a comparison result of the first accumulated result and the second accumulated result, wherein the oscillating module comprises a capacitor bank whose capacitance is adjusted in response to the frequency step.
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Specification