Application And Implementation Of FFT/IFFT Based On Mixed Radix In VDSL2 System

With the rapid development of electronic and integrated circuit technology ,digital signal processing has been widely applied in various fields, such as communication system,signal processing ,biomedical engineering, auto-control engineering and so on. Discrete Fourier Transform(DFT),Fast Fourier Transform(FFT) and Inverse Fast Fourier Transform(IFFT) have also been widely used as a basic transform in digital signal processing. Especially in recent years, FFT based on Orthogonal Frequency Division Multiplexing(OFDM) technology has arisen and this fact further pushes the investigation to a new level on FFT processor.A mixed radix algorithm is studied in this paper, which analyses this algorithm and its structure. On the basis of algorithm, a kind of FFT/IFFT processors based on pipeline architecture is designed. It functionally verifies the structure and the basic modules of the processors. The FFT/IFFT processors, which implement this structure, reduce the storage devices which are used to store sampling signal. Simultaneously, this design based on mixed radix algorithm has used the least number of multipliers, adders and memory which compares radix-4. On the other hand, the structure of the design in this paper not only supports different lengths of FFT/IFFT that the Very-high-bit-rate Digital Subscriber Loop(VDSL2) system required and its simple control operation will further reduce the number of logical switchs.In this paper, the modules of FFT/IFFT which are divided by the system are programmed with VerilogHDL, and it functionally verifies these modules under VCS platform. The results show that the whole system can be controlled with a controller and the data computing matches with data communicated operation. Comparing the results from the processor to the C model operation results, both of them are correct and the accuracy meets requirement of the design.The highest working frequency of the processors which is based on mixed radix algorithm reaches 147MHz, and the SNR is above 60dB. So the processors work well for data processing function in High-speed communication chips of VDSL2 and have good application prospects.