A CORDIC processor with efficient table-lookup schemes for rotations & on-line scale factor compensations

Abstract

In this paper, we improve our previous efficient CORDIC processor design. The improvements consist of two parts: (1) an improved table-lookup rotation scheme with a smaller table than before, and (2) a new efficient on-line table-lookup scheme for scale-factor computations and compensations which is better than the previous non-online design. Combining the improvements with the original efficient rotation angle recoding algorithm and leading-one (or zero) bit detection (for skipping redundant rotations), we obtain a lowiteration and low-complexity COREDC processor architecture. The design is more efficient than the current designs, especially in the iteration count. Simulation shows that for n-bit results, about only n/4 iterations are required. We also designed a 16-bit CORDIC processor based on 0.25 mu m UMC process. Its averaged iteration count is only 4.4 including rotation and scale factor compensations, with a total gate count of 5742 and a maximum operating frequency of 250MHz.