Implementation of DFT (Direct & FFT) Using Radix-2-4 CORDIC Algorithm

Abstract

This paper attempts to implement the fast and hardware efficient mathematical technique for computing CORDIC (Coordinate
Rotation Digital Computer) based DFT (Direct & radix-2 butterfly FFT), using original circular rotation of the mixed radix CORDIC
based method. CORDIC algorithms are hardware efficient methods of producing a wide range of trigonometric, hyperbolic, linear and
logarithmic functions using only shift and add operations. To speed up the CORDIC based DFT (Direct & radix-2 butterfly FFT)
calculation a new method has been proposed. This new scheme reduces the last N / 2 CORDIC iterations to N / 4 by using radix-
2-4 CORDIC algorithm, where the required precision is N. Radix-2-4 CORDIC algorithm uses radix-4 micro rotation in the second
half of the CORDIC iterations. This scheme reduces the number of iterations in the CORDIC rotation unit by about 25%. Reduction of
iterations also trims down the calculation time.