Design of 2K/4K/8K-point FFT processor based on cordic algorithm in OFDM receiver

In this paper, the architecture and the implementation of a 2K/4K/8K-point complex fast Fourier transform (FFT) processor for OFDM system are presented. The processor can perform 8K-point FFT every 273 mus, and 2K-point every 68.26 mus at 30 MHz which is enough for OFDM symbol rate. The architecture is based on the Cooley-Tukey algorithm for decomposing the long DFT into short length multi-dimensional DFTs. The transposition and shuffle memories are used for the implementation of multi-dimensional transforms. The CORDIC processor is employed for the twiddle factor multiplications in each dimension. A new twiddle factor generation method is also proposed for saving the size of ROM required for storing the twiddle factors.