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US 6,643,323 B1Granted
Digital filtering method
AssigneeTexas Instruments Incorporated
InventorRustin W. Allred
Life of this patent
Estimating the term…
Abstract
A method of implementing a digital filter utilizes a fast and accurate reciprocal estimate function to generate and recharacterize the digital filter on the fly. The reciprocal estimate function operates to synthesize a digital filter rapidly and efficiently without the necessity for trigonometric and/or division capabilities, thereby preserving integrated circuit real-estate.
Claims22
A method of implementing a digital filter comprising the steps of:
- (a) providing a first digital filter characteristic having a value x that comprises a denominator portion for a filter function having a numerator portion and a denominator portion, wherein the filter function is associated with a digital filter element parameter;
- (b) providing a predetermined constant s having a numerical value between about 0.5 and about 0.6;
- (c) generating a constant n having a value determined by the position of the most significant bit of a binary number representation of the value of x;
- (d) generating a reciprocal estimate for x using the functional relationship represented by:
- 1/x=(1/s)*2−n−2−(x−2n)*2−2n−1+2−n−1;
- (e) generating a digital filter element parameter via multiplying the reciprocal estimate for x by a numerical value of the numerator portion of the filter function;
- and
- (f) characterizing a digital filter element via the generated element parameter to implement the digital filter.
5 more elements
A method of generating a digital filter comprising the steps of:
- (a) providing a first digital filter characteristic comprising one portion of a denominator portion for a filter function having a numerator portion and a denominator portion, wherein the filter function is associated with a digital filter element parameter;
- (b) providing a second digital filter characteristic comprising another portion of the denominator portion for the filter function;
- (c) generating a value x by summing a value associated with the second digital filter characteristic and a value associated with the first digital filter characteristic;
- (d) providing a predetermined constant s having a numerical value between about 0.5 and about 0.6;
- (e) generating a constant n having a value determined by the position of the most significant bit of a binary number representation of the value of x;
- (f) generating a reciprocal estimate for x using the functional relationship represented by:
- 1/x=(1/s)*2−n−2−(x−2n)*2−2n−1+2−n−1;
- (g) generating a digital filter element parameter via multiplying the reciprocal estimate for x by a numerical value of the numerator portion of the filter function;
- and
- (h) characterizing the digital filter element via the generated element parameter to implement the digital filter.
7 more elements
A method of generating a digital filter comprising the steps of:
- (a) providing at least one digital filter characteristic comprising at least one portion of a numerator portion for a filter function having a numerator portion and a denominator portion, wherein the filter function is associated with a digital filter element parameter;
- (b) providing at least one digital filter characteristic comprising at least one portion of a denominator portion of the filter function;
- (c) generating a value x associated with the at least one digital filter characteristic comprising at least one portion of the denominator portion of the filter function;
- (d) providing a predetermined constant s having a numerical value between about 0.5 and about 0.6;
- (e) generating a.constant n having a value determined by the position of the most significant bit of a binary number representation of the value of x;
- (f) generating a reciprocal estimate for x using the functional relationship represented by:
- 1/x=(1/s)*2−n−2−(x−2n)*2−2n−1+2−n−1;
- (g) generating a digital filter element parameter via multiplying the reciprocal estimate for x by a numerical value of the numerator portion of the filter function;
- and
- (h) characterizing the digital filter element via the generated element parameter to implement the digital filter.
7 more elements
Dependencies are inferred from the claim text.