改进的结构进化无限冲激响应数字滤波器设计方法

为了进一步提高无限冲激击响应（IIR）数字滤波器的性能，提出了一种基于结构和参数同时进化的IIR数字滤波器设计方法。首先，通过遗传算法（GA）得到初始滤波器结构；然后，利用差分进化（DE）算法优化滤波器参数；最后，通过动态调整个体搜索步长和双向试探搜索的改进寻优算法对滤波器参数进一步优化，并将该算法用于低通、高通数字滤波器的设计。同基于遗传算法结构进化的IIR滤波器方法相比，继续利用差分进化算法和改进的寻优算法优化乘法器参数得到的低通数字滤波器的通带性能相差不大，但是过渡带宽度减小了65%，阻带最小衰减下降了36.48 dB；得到的高通数字滤波器通带波纹减少了75%，过渡带宽度减小了44%，阻带最小衰减下降了12.13 dB。实验仿真结果表明，所提方法可以获得性能更佳的滤波器，是一种有效可行的IIR数字滤波器的设计方法。

Improved design method for infinite impulse response digital filter based on structure evolution

In order to further improve the performance of Infinite Impulse Response (IIR) digital filter, a design method of the IIR digital filter based on structure evolution and parameter evolution was proposed. Firstly, initial filter structure was got by using Genetic Algorithm (GA). Then, Differential Evolution (DE) was used to optimize the parameters of the filter. Finally, an improved optimization strategy was used to further optimize the parameters of the filter by using adjustment search-step and bidirectional heuristic search. Furthermore, the proposed method was applied to the design of low-pass filter and high-pass filter. Compared with the design method based on GA, the pass-band performance of low-pass filter based on the proposed method is not much different from that of the previous algorithm, however, the transition zone width of it is reduced by 65%, the minimum stop-band attenuation of it was reduced by 36.48 dB; the pass-band ripple of high-pass filter based on the proposed method is reduced by 75%, the transition zone width of it is reduced by 44%, and the minimum stop-band attenuation of it is reduced by 12.13 dB. Simulation results show that the proposed method can get effective filters with better performance, therefore it is suitable for the IIR digital filter design.