广义Chebyshev滤波器的边带优化设计

Optimization Design of Band-Edge Selectivity for General Chebyshev Filter

为获得小型化、高性能的滤波器,在分析传输零点对滤波器选择性影响的基础上,提出了一种阶数最小、边带选择性最大的广义Chebyshev滤波器设计方法.通过利用传输零点与带外等波纹峰值频率的关系,实现了广义Chebyshev函数传输零点的精确设计.以矩形三腔滤波器的优化为例,在满足设计指标的基础上,实现了该滤波器最大选择性的设计,实测传输零点为850.200 MHz,带外等波纹峰值频率为824 MHz,与传统设计相比,缩短了过渡带,提高了滤波器的选择性.实例结果表明,该设计方法能有效改善滤波器的性能.

In order to get miniaturized high-performance filters,based on analyzing the impact of transmission zeros on the selectivity of a filter a new design method was proposed for maximizing the band-edge selectivity of general Chebyshev filters with a minimum filter order.Based on maximizing the band-edge selectivity,the transmission zero of a general Chebyshev filter was obtained accurately from the relationship between the transmission zeros and the frequencies of magnitude characteristic extreme values.A rectangular three-cavity filter,as an example,was optimized.On the basis of meeting the design specifications,the maximum selectivity of the filter was achieved.The measured transmission zero is 850.200 MHz,and the frequency of magnitude characteristic extreme value is 824 MHz.Compared with the traditional filter,the general Chebyshev filter has a narrow transition band and improves the selectivity.The example show that the design method can effectively improve the performance of a filter.