Apparatus providing FFT/IFFT for OFDM by Dual Mode and the Controlling Method thereof

The present invention discloses an FFT / IFFT dual mode device for OFDM and a control method thereof. The present invention receives 2N (0 ≤ N, integer) data each consisting of a pair of real and imaginary parts in parallel and outputs N odd-numbered data and N even-numbered data in fast Fourier transform mode. And an input buffer multiplexer for outputting the real part and the imaginary part of the N odd data and the N even data in the inverse fast Fourier transform mode, and the N odd data and the N even data, respectively. First and second N-point Radix-4 FFT processors that receive fast fast Fourier transforms, and first and second Radix-4 butterfly operations on the outputs of the first and second N-point Radix-4 FFT processors, respectively. A butterfly unit and the first and second Radix-4 butterfly unit outputs in the fast Fourier transform mode to output 2N pieces of data; In that it includes an output buffer, a multiplexer, and a control part for controlling the fast Fourier transform mode, or an inverse fast Fourier transform mode and outputting the aligned one of 2N pieces of data the real and imaginary parts of the exchange in the Fourier transform mode it may have its features. The FFT / IFFT dual mode device for OFDM and its control method according to the present invention process two 2N-point fast Fourier transforms using the DIT (Decimation In Time) method in parallel by M time, so that the time delay is low and the system operation speed is low. The hardware is easy to implement and control and the performance is excellent. OFDM, FFT / IFFT Dual-Mode, FFT Processors, Butterfly Math, Tweed Factor