Programmable N-Point FFT Design

Abstract—The FFT, Fast Fourier Transform is the most ubiquitous algorithm used for signal analysis in present-day communication systems (Example: OFDM). The general principle of FFT Algorithms is to use a Divide and Conquer approach that effectively reduces operation count. The FFT is generally computed either using a single radix or by mixed radix algorithms. Several optimization techniques have been proposed to increase efficiency while computing the Fourier Transform. This paper develops a reconfigurable FFT processor that can take any number of points as input, and is not limited to sequence lengths that are powers of the radix. The paper compares the factorized mixed radix approach with the single radix approach for computation of the FFT of a truly N-point sequence and shows that the mixed-radix approach yields better performance results. The test designs were developed in VHDL, verified in Matlab and Modelsim, and implemented using Xilinx Virtex5 LX110T FPGA.

Index Terms—Fast fourier transform, mixed radix, cooley-Tukey algorithm, prime-factor algorithm, word length effects.

The authors are with Department of Electronics and Communication Engineering Amrita Vishwa Vidyapeetham, India (e-mail: ramesh.amrita@gmail.com).

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Cite: Ramesh Bhakthavatchalu, Meera Viswanath, Pallavi Venugopal M., and Anju R., "Programmable N-Point FFT Design," Lecture Notes on Software Engineering vol. 2, no. 3, pp. 247-250, 2014.