The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 07, 2002
Filed:
Jun. 18, 1999
Gwangwoo Choe, Austin, TX (US);
James R. MacDonald, Austin, TX (US);
Advanced Micro Devices, Inc., Sunnyvale, CA (US);
Abstract
A system and method for evaluating one or more functions using a succession of CORDIC stages/iterations followed by a residual rotation. The succession of CORDIC stages are preferably partitioned into (a) a Z path which operates on an input angle and generates an output angle, and (b) an X/Y path which operates on an input point and generates an output point. The residual rotation rotates the output point by the output angle to generate a resultant point using a small angle approximation for sine and an accurate evaluation for sine of the output angle. The number of CORDIC stages in the succession is chosen so that the error in the coordinates of the resultant point induced by the approximation of sine is smaller than a desired amount. In particular, the number of CORDIC stages in the succession is chosen to be greater than or equal to (N+1)/3 in order to guarantee N bits of precision in coordinates of the resultant point. The Z path has a propagation time which is smaller than the X/Y path. This allows the cosine computation unit to generate the cosine of the output angle prior to the time when the X/Y path generates the output point. Thus, the residual rotation may be performed immediately upon generation of the output point.