A Computation Method of High-AccuracySine &Cosine Function Based on Lookup-table and SF CORDIC Algorithm
Mou Shengme · Computer and Digital Engineering · 2014
Lookup-table and CORDIC algorithm are usually used to compute sine cosine function on FPGA.The former is easy to implement with short output delay,but large amount of memory units are needed and entries grow exponentially with the accuracy of input angles.The latter can achieve higher accuracy with less memory units,but needs more hardware resource and has long output delay.A novel method combined with lookup table and SF CORDIC algorithm is proposed, which acquires initial iteration vector from lookup table and applies SF CORDIC algorithm to the residual angle.The address width of lookup-table and the number of iterations is reduced almost by half comparing with traditional lookup table method and CORDIC algorithm respectively.SF CORDIC algorithm can significantly reduce the hardware consumption and rounding error of datapath xand yby using coefficient 0or 1,and shorten the pipeline delay by generating each residual angle of datapath zin advance with altrenate addition and subtraction.The design,simulation and error analysis of the novel method have been completed based on FPGA,which indicates that it can achieve higher accuracy and lower output delay with less hardware resource and few memory units.