Quadrature modulated phase-locked loop
First Claim
Patent Images
1. A phase-locked loop (PLL) phase modulator comprising:
- an oscillator for generating a phase modulated carrier signal in response to a regulating signal;
a quadrature modulator for combining the phase modulated carrier signal and information signals to produce a quadrature modulated signal; and
a phase comparator for comparing the phase of the quadrature modulated signal with the phase of a reference frequency signal to produce the regulating signal.
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Abstract
A phase-locked loop incorporates a quadrature modulator for generating constant envelope phase or frequency modulation. Locating the quadrature modulator within the feedback loop or feeding the output signal of the quadrature modulator into the feedback loop permits accurate constant envelope phase modulation of the loop reference oscillator and completely suppresses undesired AM and PM components of the modulated signal.
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Citations
35 Claims
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1. A phase-locked loop (PLL) phase modulator comprising:
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an oscillator for generating a phase modulated carrier signal in response to a regulating signal; a quadrature modulator for combining the phase modulated carrier signal and information signals to produce a quadrature modulated signal; and a phase comparator for comparing the phase of the quadrature modulated signal with the phase of a reference frequency signal to produce the regulating signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A phase-locked loop phase modulator comprising:
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a reference oscillator for generating a phase modulated carrier signal in response to a regulating signal; a quadrature modulator for combining a first reference signal and information signals to produce a quadrature modulated signal; a mixer for mixing the phase modulated carrier signal and the quadrature modulated signal; and a phase comparator for comparing the phase of an output signal of the mixer with the phase of a second reference signal to produce the regulating signal. - View Dependent Claims (17, 18, 19, 20)
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21. A phase-locked loop phase modulator comprising:
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an oscillator for generating a phase modulated carrier signal in response to a regulating signal; a quadrature modulator for combining a reference signal and information signals to produce a quadrature modulated signal; and a phase comparator for comparing the phase of the phase modulated carrier signal with the phase of the quadrature modulated signal to produce the regulating signal. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A phase modulation method for maintaining a constant envelope oscillator output signal generated by an oscillator in a phase-locked loop (PLL) comprising:
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sampling the oscillator output signal to generate a PLL feedback signal; quadrature modulating the PLL feedback signal with in-phase and quadrature information signals, comparing the phase of the quadrature modulated signal with the phase of a reference signal to determine a difference signal; and regulating the oscillator using the difference signal, wherein the oscillator output signal is substantially free of spurious amplitude modulation. - View Dependent Claims (28, 29, 30)
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31. A phase modulation method for maintaining a constant envelope oscillator output signal generated by an oscillator in a phase-locked loop (PLL) comprising:
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sampling the oscillator output signal to generate a PLL feedback signal; quadrature modulating a first reference signal based on in-phase and quadrature information signals to generate a quadrature modulated signal; combining the quadrature modulated signal with the PLL feedback signal; comparing the phase of the combined signal with the phase of a second reference signal to determine a difference signal; and regulating the oscillator using the difference signal, wherein the oscillator output signal is substantially free of spurious amplitude modulation. - View Dependent Claims (32, 33)
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34. A phase modulation method for use in a phase locked loop comprising:
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generating a constant envelope reference oscillation signal; phase modulating the reference oscillation signal with an information signal; translating any spurious amplitude modulation generated in the phase modulating step into spurious phase modulation components; and comparing the phase of the phase modulated signal with the phase of a reference signal to generate a control signal for controlling the PLL, wherein the spurious phase modulation components are removed in the comparing step.
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35. A phase-locked loop (PLL) phase modulator, comprising:
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an oscillator for generating a phase modulated output signal in response to a regulating signal; a quadrature modulator for combining in-phase and quadrature information signals with the phase modulated output signal to generate a phase modulated input signal; and a phase comparator for comparing the phase of the phase modulated input signal with the phase of a reference frequency to produce the regulating signal, wherein a transfer function defined as the phase modulated output signal divided by the phase modulated input signal compensates for undesired amplitude or phase modulations generated by the quadrature modulator.
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Specification