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Constant-Factor Redundant CORDIC for Angle Calculation and Rotation
August 1992 (vol. 41 no. 8)
pp. 1016-1025

A constant-factor redundant-CORDIC (CFR-CORDIC) scheme, where the scale factor is kept constant while an angle for plane rotations is computed, is developed. The direction of rotation is determined from an estimate of the sign, and convergence is assured by suitably placed correcting iterations. The number of iterations in the CORDIC rotation unit is reduced by about 25% by expressing the direction of the rotation in radix-2 and radix-4, and conversion to conventional representation is done on the fly. The performance of CFR-CORDIC is estimated and compared with that of previously proposed schemes. It is found to provide an execution time similar to that of redundant CORDIC with a variable scaling factor, with a significant saving in area.

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Index Terms:
rotation direction; angle calculation; constant-factor redundant-CORDIC; scale factor; plane rotations; convergence; correcting iterations; radix-2; radix-4; algorithm theory; convergence of numerical methods; digital arithmetic; iterative methods; number theory.
J.-A. Lee, T. Lang, "Constant-Factor Redundant CORDIC for Angle Calculation and Rotation," IEEE Transactions on Computers, vol. 41, no. 8, pp. 1016-1025, Aug. 1992, doi:10.1109/12.156544
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