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Fractional-division synthesizer for a voice/data communications systems

  • US 5,065,408 A
  • Filed: 04/26/1990
  • Issued: 11/12/1991
  • Est. Priority Date: 04/26/1990
  • Status: Expired due to Term
First Claim
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1. A fractional-division synthesizer for a digital radio transceiver, the synthesizer providing an output signal having a non-integer frequency relationship to a reference signal frequency, the fractional-division synthesizer comprising:

  • a phase comparator having at least a first input and at least a first output;

    a programmable frequency divider with a non-integer divisor having a value of the sum of an integer,N, and a fraction determined by the ratio of integer, {n/d}, said programmable frequency divider having at least a first input and at least a first output, said first output of said programmable frequency divider coupled to said first input of said frequency comparator, said programmable frequency divider dividing the frequency of said output signal;

    means for generating an output signal having a first frequency when said non-integer divisor has a first value determined by a first integer value of n and for generating an output signal having a second frequency when said non-integer divisor has a second value determined by the next larger integer value of n, an input of said means for generating coupled to said first output of said phase comparator, an output of said means for generating an output signal coupled to said first input of said programmable frequency divider;

    means for generating a first reference signal;

    means, responsive to said means for generating a first reference signal, for producing a second reference signal coupled to a second input of said phase comparator, said second reference signal having a frequency integerly related to the product of d times the difference of said first output signal frequency and said second output signal frequency; and

    means, responsive to said means for generating a first reference signal, for producing a third reference signal coupled to a digital portion of said digital transceiver, said third reference signal having a frequency algebraically related to said first reference signal frequency.

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