An efficient FFT twiddle factor generator

Twiddle factor (TF) generator is a key component in IFFT/FFT computation for current OFDM-based wireless and wireline communication systems, such as IEEE 802.11a/g, 802.16, VDSL, DVB, DAB systems. In this paper, we propose an efficient TF generator design. The proposed design combines an efficient conventional recursive sine/cosine function generation algorithm with a small compensation lookup table. The compensation table solves the error propagation problem of a recursive TF generator. It also costs less area than the existing modified recursive sine/cosine function generator. The proposed design requires only two constant multipliers, two adders, and two correction tables, which is smaller than those polynomial-based complex sine function generators. Simulation results show that the proposed design is favourable over the existing TF generators for general FFT lengths in practical applications, except for small lengths such as 64 up to 512. For those small FFT lengths, ROM-based is a better choice.