• 一种混合型流水线架构的FFT加速引擎设计

    Design of a hybrid pipeline architecture FFT acceleration engine

    • 快速傅里叶变换(FFT)技术广泛应用于滤波、通信以及数字频谱分析等领域。面向FFT运算硬件加速需求,首先以离散傅里叶变换中旋转因子所具有的对称性、周期性以及可约性为起点,研究了FFT的算法原理,重点是长序列离散傅里叶变换到短序列离散傅里叶变换的分解和抽取。在此基础上对顺序处理架构、流水线架构、并行迭代架构和阵列架构这4类典型的FFT加速引擎硬件架构进行对比分析,综合考虑运算速度、数据调度控制的复杂性和资源开销,采用流水线架构进行FFT加速引擎设计;针对单路延迟反馈结构中蝶形运算单元和复乘单元输出冲突的问题,提出一种9级单路延迟反馈+4级多路延迟置换的13级混合型流水线架构。设计的FFT加速引擎分别在65 nm和28 nm工艺下实现,最高工作频率为1 GHz、计算性能达到260 Gflops。

       

      Abstract: Fast Fourier transform (FFT) technology is widely used in the fields of filtering, communication and digital spectrum analysis. In order to realize the hardware acceleration of FFT, this paper first studies the principle of FFT algorithm. The research is based on the symmetry, periodicity and reducibility of rotation factor in Discrete Fourier Transform. The focus of the research is the decomposition and extraction from long sequence Discrete Fourier Transform to short sequence Discrete Fourier Transform. Four typical FFT acceleration engine hardware architectures are further studied, including sequential processing architecture, pipeline architecture, parallel iterative architecture and array architecture. Taking into account computational speed, complexity of data scheduling, and resource overhead, this paper adopts a pipeline architecture. In single delay feedback structure, the output of the butterfly operation unit and the complex multiplication unit may conflict. Therefore, this article proposes a 13-stage hybrid pipelined architecture which combines 9-stage single-path delay feedback + 4-stage multi-path delay commutator. The FFT acceleration engine designed in this article is implemented in 65 nm process and 28 nm process respectively. The maximum operating frequency is 1 GHz and the computing performance reaches 260 Gflops.

       

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