Linear wideband phase modulation system
First Claim
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1. Apparatus for linear phase modulation utilizing a phase-locked loop, the apparatus comprising:
- a digital limiting circuit that restricts a range of a modulation signal that is coupled to a voltage controlled oscillator (VCO) associated with the phase-locked loop; and
a linearizing circuit that reshapes the modulation signal to improve linearity;
wherein the digital limiting circuit comprises a circuit disposed to;
receive a set of digital samples representative of the FM value of the modulation signal;
determine if the value of a first sample of the set of digital samples exceeds a predefined threshold; and
responsive to said determining, adjust the values of the first sample and a second sample of the set of digital samples.
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Abstract
Linear wideband phase modulation system. Apparatus is provided for linear phase modulation utilizing a phase-locked loop. The apparatus includes a limiting circuit that restricts a range of a modulation signal that is coupled to a voltage controlled oscillator (VCO) associated with the phase-locked loop, and a linearizing circuit that reshapes the modulation signal to improve linearity.
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Citations
29 Claims
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1. Apparatus for linear phase modulation utilizing a phase-locked loop, the apparatus comprising:
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a digital limiting circuit that restricts a range of a modulation signal that is coupled to a voltage controlled oscillator (VCO) associated with the phase-locked loop; and a linearizing circuit that reshapes the modulation signal to improve linearity; wherein the digital limiting circuit comprises a circuit disposed to; receive a set of digital samples representative of the FM value of the modulation signal; determine if the value of a first sample of the set of digital samples exceeds a predefined threshold; and responsive to said determining, adjust the values of the first sample and a second sample of the set of digital samples. - View Dependent Claims (2, 3, 4, 5)
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6. Apparatus for linear phase modulation utilizing a phase-locked loop, the apparatus comprising:
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a limiting circuit that restricts a range of a modulation signal that is coupled to an input of a voltage controlled oscillator (VCO) associated with the phase-locked loop; and a linearizing circuit that reshapes the modulation signal to improve linearity; wherein the linearizing circuit is disposed to predistort the modulation signal in accordance with a polynomial predistortion characteristic, said polynomial predistortion characteristic selected to offset a VCO non-linearity. - View Dependent Claims (7, 8, 9, 10)
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11. A method for providing linear phase modulation utilizing a phase-locked loop having a voltage controlled oscillator, the method comprising:
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limiting a range of a modulation signal that is coupled to the VCO; and linearizing the modulation signal input to improve linearity; wherein the limiting comprises; receiving a set of digital samples representative of the FM value of the modulation signal; determining if the value of a first sample of the set of digital samples exceeds a predefined threshold; and responsive to said determining, adjusting the values of the first sample and a second sample of the set of digital samples. - View Dependent Claims (12, 13, 14, 15)
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16. A method for providing linear phase modulation utilizing a phase-locked loop having a voltage controlled oscillator (VCO), the method comprising:
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limiting a range of a modulation signal that is coupled to an input of the VCO; and linearizing the modulation signal input to improve linearity; wherein the linearizing comprises predistorting the modulation signal in accordance with a polynomial predistortion characteristic, said polynomial predistortion characteristic selected to offset a VCO non-linearity. - View Dependent Claims (17, 18, 19)
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20. A communication device comprising:
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a phase-locked loop circuit including a voltage controlled oscillator (VCO); and a compensation circuit for compensating for non-linearities in the VCO, said compensation circuit comprising; a digital limiter circuit for restricting the FM range of a modulation signal coupled to the VCO, said limiter circuit disposed to receive a set of digital samples representative of the FM value of the modulation signal, determine if the value of a first sample of the set of digital samples exceeds a predefined threshold, and, responsive to said determining, adjust the values of the first sample and a second sample of the set of digital samples; and a linearization circuit disposed to predistort the set of digital samples representative of the FM value of the modulation signal in accordance with a polynomial predistortion characteristic, said polynomial predistortion characteristic selected to offset a VCO non-linearity. - View Dependent Claims (21, 22, 23, 24)
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25. A communication device comprising:
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A phase-locked loop circuit including a voltage controlled oscillator; and A compensation circuit for compensating for non-linearities in the VCO, said compensating circuit comprising; a limiting circuit that restricts a range of a modulation signal that is coupled to an input of a voltage controlled oscillator (VCO) associated with the phase-locked loop; and a linearizing circuit that reshapes the modulation signal to improve linearity; wherein the linearizing circuit is disposed to predistort the modulation signal in accordance with a polynomial predistortion characteristic, said polynomial predistortion characteristic selected to offset a VCO non-linearity. - View Dependent Claims (26, 27, 28, 29)
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Specification