Method of generating sine/cosine function and apparatus using the same for use in digital signal processor
First Claim
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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Abstract
A method of generating sine/cosine function and an apparatus using the same in digital signal processor are disclosed. The 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 the 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 the step d) according to the first bit group. Therefore, the capacity of memory needed for the look-up table can be decreased without an excessive increase in hardware.
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Citations
12 Claims
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1. A method for generating sine/cosine function values corresponding to a first digital phase values, comprising the steps of:
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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. - View Dependent Claims (2, 3, 4)
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5. An apparatus for generating sine/cosine function values corresponding to a first digital phase values, comprising:
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input means for 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;memory means having as much storage locations as determined by the second bit group, for sequentially storing one of sine and cosine function values for phase values of any one quadrant, in the form of a look-up table; address generating means for generating a first address signal from the second bit group supplied from said input means and a second address signal by inverting the second bit group; a first function value generator for generating sine and cosine function values for the same phase value corresponding to both the first and second address signals by accessing said memory means, at each second clock being faster than the first clock; and a second function value generator for generating sine and cosine function values for the first digital phase values by multiplexing the sine and cosine function values obtained in said first function value generator according to the first bit group supplied from said input means. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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Specification