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Method of generating sine/cosine function and apparatus using the same for use in digital signal processor

  • US 5,954,787 A
  • Filed: 12/01/1997
  • Issued: 09/21/1999
  • Est. Priority Date: 12/26/1996
  • Status: Expired due to Term
First Claim
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1. A method for generating sine/cosine function values corresponding to a first digital phase values, comprising the steps of:

  • a) receiving a second digital phase values, obtained by performing 2π

    modulo operation for the first digital phase values, having the first bit group representing a quadrant and the second bit group representing a phase value, at each first clock;

    b) forming a look-up table having as much storage locations as determined by the second bit group, for converting phase values of any one quadrant to one of sine and cosine function values;

    c) generating a first address signal from the second bit group and a second address signal by inverting the second bit group;

    d) generating sine and cosine function values for the same phase value corresponding to both the first and second address signals by accessing said look-up table, at each second clock being faster than the first clock; and

    e) generating sine and cosine function values for the first digital phase values by multiplexing the sine and cosine function values obtained in said step d) according to the first bit group.

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