High-speed CORDIC based on an overlapped architecture and a novel sigma-prediction method

This paper presents architectural and algorithmic approaches for achieving high-speed CORDIC processing in both of the two operating modes: vectoring and rotation. For vectoring mode CORDIC processing, a modified architecture is proposed, which aims at reduction of computation time by overlapping th e stages for redundant addition and selection of rotation direction. In add ition, a novel rotation direction prediction scheme for rotation mode CORDI C is presented. The method is based on approximation of the binary angle in put to a number with the arctangent weights (tan(-1) 2(-i)). The implementa tion is designed to keep the fast timing characteristics of redundant arith metic in the x/y path of the CORDIC processing. The characteristics are ana lyzed with respect to latency time and area, and compared with those obtain ed by conventional CORDIC implementations. The results show that the propos ed techniques reduce not only the block latency but also the overall comput ation time. Thus, they achieve higher throughput in pipelining.