一种基于FFT的超宽带数字正交变换算法及实现

Super-wide band digital I/Q transform algorithm based on FFT and its implementation

本文提出了一种基于FFT的超宽带数字正交算法。利用FPGA的丰富资源,采用并行处理技术,构造复合FFT变换,进行速度匹配,在硬件中实现了该正交变换算法。与其他数字正交变换技术相比,该方法具有输出I/Q信号相位正交性好、幅度误差小的优点。结合算法FPGA硬件实现需要,本文通过将一个256点的FFT(IFFT)分解成8个32点FFT(IFFT)的并行结构,实现了算法的并行处理。在XILINX公司VirtexIV系列FPGA器件中的硬件仿真表明,该设计实现了对采样率为1.2GHz、带宽为600MHz的超宽带实信号的连续、实时正交变换处理。

A super-wide band digital I/Q transform algorithm is proposed in this paper. This algorithm is realized in FPGA using a hybrid FFT structure, which profits from the parallel processing technology and luxuriant resource in FPGA. Using this algorithm the different speeds inside and outside FPGA are matched. Comparing with other I/Q transform technology, our method has the advantages of good quadrature property and minimal amplitude error. In order to meet the requirement of FPGA implementation, a 256 point FFT is decomposed into 8 parallel 32 point FFTs, and the parallel processing is realized. The after place and route simulation result in VirtexIV series FPGA from XILINX Company indicates that this design achieves a continuous, real time I/Q transform for a super-wide band signal with 1.2 GHz sampling rate and 600 MHz band width.