基于分形技术的阶跃阻抗微带低通滤波器设计

内容简介：设计阶跃阻抗微带低通滤波器时，由于阶跃阻抗微带线结构的不连续性，会导致版图仿真与电路原理图仿真结果相差很远。为了解决这一问题，提出先对阶跃阻抗微带线的结构参数进行预处理，然后引入分形技术对低阻抗微带线的版图结构作进一步优化的设计方法，利用分形结构成阶梯锯齿状分布的线宽来改善滤波器的通带特性，而又几乎不影响滤波器的阻带特性，获得了满意的滤波性能；以一个5阶契比雪夫型阶跃阻抗微带低通滤波器设计为例，仿真结果表明：滤波器通带内的最大反射损耗从-0．87dB降低到-15．22dB。与直接采用分形结构的设计方法相比，该方法有利于减少分形结构的迭代次数，降低加工精度要求，从而降低制作成本。

Abstract：When designing the stepped impedance micro-strip low-pass filter, the layout simulation results of the filter are quite different from that of the schematic one, since the in-continuity of the stepped impedance. To solve this problem, the structure parameters of the stepped impedance micro-strip line are pre-modified, then the layout of the low impedance micro-strip line is optimized by fractal shape technique. Since the gradual changes of the step, the pass-band performance is improved, and the stop-band performance is hardly deteriorated. The simulation results indicate that the performance of the fractal-shaped structure filter can meet the design requirements well. By the example of a 5 order Chebyshev low-pass filter de- sign, the simulated results indicate that the maximum value of the pass-band, reflec- tion loss is reduced from --0. 87 dB to --15.22 dB. Compared to the method of em- ploying fractal shape structure directly, the presented method is propitious to reduce the iterative times and lower the demand of process precision, so the manufacture cost can be reduced.

作者：杨维明, 吴姣, 张劲, 陈军, 杨安胜,

关键词：阶跃阻抗, 低通滤波器, 微带线, 分形技术