A fast direction sequence generation method for CORDIC processors

This paper describes a new direction sequence generation method for the circular CORDIC algorithm. A conventional approach employs an angle computation algorithm to control the direction of rotation in the form of a sign sequence, where the sign generation is a bottle-neck for the fast implementations. The proposed method reduces the number of sequential computations by employing a new angle representation model and linearizing the arctangent function in small angles. The direction sequence can be generated by about a third of the iterative computations required in the conventional algorithm, which also reduces the hardware requirements as much. Especially, this algorithm is attractive when pipelining is not allowed for feedback control, such as found in phase tracking applications. A VLSI implementation example for a high-speed quadrature demodulator is also discussed