The split-radix fast Fourier transforms with radix-4 butterfly units

We present a split radix fast Fourier transform (FFT) algorithm consisting of radix-4 butterflies. The major advantages of the proposed algorithm include: i). The proposed algorithm consists of mixed radix butterflies, whose structure is more regular than the conventional split radix algorithm. ii). The proposed algorithm is asymptomatically equal computation amount to the split radix algorithm, and is fewer operations than the radix-4 algorithms. iii). The proposed algorithm is in the conjugate-pair version, which requires less memory access than the conventional FFT algorithms.