小型化有耗和频变耦合滤波器研究

发布时间：2018-04-22 13:50

本文选题：耦合矩阵 + 有耗滤波器　；参考：《上海交通大学》2015年硕士论文

【摘要】：现代微波通信系统往往需要高性能小型化的滤波器,同时兼顾易集成和低成本的特点。元件的小型化通常会降低谐振器的无载品质因素(Qu值),而低Qu值谐振器将使滤波器,特别是窄带滤波器,性能退化,具体表现为通带插损增加、边带变圆滑和带内波纹部分或全部消失等。为了克服这些问题,近年来提出了有耗综合技术,即在设计中考虑谐振器的有限Qu值,优化滤波器的频率选择性和通带平坦度。另一方面,增加传输零点可以使低阶响应具有较高的频率选择性,从而实现滤波器的小型化。实现传输零点的传统方法有交叉耦合(包括源-负载耦合)、非谐振节点、多模谐振器和外部抽头耦合等。频变耦合可以在不引入交叉耦合的情况下,利用传统耦合结构产生更多的传输零点,提高频率选择性。本文从有耗综合和频变耦合两方面,研究滤波器的小型化,具体包括:(1)基于非一致Qu值方法的三模有耗滤波器设计。理论研究和仿真分析结果表明,预失真技术会使带内反射严重退化,而有耗耦合矩阵综合的非纯电抗耦合结构实现难度较大。相比较而言,非一致Qu值方法实现简单,产生的副作用相对较小。三模谐振器中的各谐振模式正交,因此在滤波器中响应独立,可以采用非一致Qu值设计带内平坦的滤波器。通过表贴电阻调整奇模谐振器Qu值,合理分配谐振器损耗,从而改善滤波器的带内平坦度。(2)基于频变耦合的滤波器和滤波功分器设计。根据N+2阶频变耦合矩阵与传统横向耦合矩阵的相似性,采用特征值逼近优化耦合矩阵。分析了频变K/J变换器的线性近似集总和传输线模型。在此基础上设计三阶主线频变耦合滤波器,并应用奇偶模理论设计了四路滤波功分器,即具有高频率选择性又有较高的带内隔离度。研究表明,由于多模谐振器为横向拓扑结构,合理调节谐振模式Qu值能够明显改善滤波器的带内平坦度。而结合频变耦合的多路滤波功分器能够集成实现滤波和功分两种功能,从而达到元件小型化的目的。
[Abstract]:Modern microwave communication systems often require high performance and miniaturization filters, while taking into account the characteristics of easy integration and low cost. The miniaturization of the components usually reduces the unloaded quality factor of the resonator and the low Qu value resonator degrades the performance of the filter, especially the narrowband filter, which is characterized by an increase in the passband insertion loss. The sideband is smooth and the corrugation in the band is partially or completely disappeared. In order to overcome these problems, a lossy synthesis technique is proposed in recent years, that is, the finite qu value of the resonator is considered in the design, and the frequency selectivity and pass band flatness of the filter are optimized. On the other hand, increasing the transmission zeros can make the low order response have higher frequency selectivity and realize the miniaturization of the filter. The traditional methods to realize transmission zeros include cross-coupling (including source-load coupling, non-resonant node, multi-mode resonator and external tap coupling, etc.) Frequency varying coupling can generate more transmission zeros and improve frequency selectivity without cross-coupling. In this paper, the miniaturization of filters is studied from the aspects of lossy synthesis and frequency variation coupling, including the design of three-mode lossy filters based on non-uniform qu value method. The theoretical research and simulation results show that the pre-distortion technique will seriously degenerate the in-band reflection, but it is difficult to realize the non-pure reactance coupling structure with lossy coupling matrix synthesis. By comparison, the non-uniform qu value method is simple to implement and produces relatively small side effects. The resonant modes in the three-mode resonator are orthogonal, so the response in the filter is independent, and the in-band flat filter can be designed by using the non-uniform qu value. By adjusting the Qu value of odd-mode resonator by the surface resistance, the loss of the resonator is allocated reasonably, thus the in-band flatness of the filter is improved. (2) the design of filter and filter power divider based on frequency-varying coupling is presented. According to the similarity between the N _ 2-order frequency varying coupling matrix and the traditional transverse coupling matrix, the eigenvalues are used to approximate the optimized coupling matrix. The linear approximate set summation transmission line model of frequency-varying K / J converter is analyzed. On this basis, the third order main line frequency variable coupling filter is designed, and the four-way filter power divider is designed by using the odd-even mode theory, which has high frequency selectivity and high in-band isolation. The results show that, because the multimode resonator is a transverse topology, the in-band flatness of the filter can be obviously improved by adjusting the resonant mode qu value properly. The multi-channel filter power divider combined with frequency-varying coupling can realize the functions of filtering and power division, so as to achieve the purpose of miniaturization of the components.
【学位授予单位】：上海交通大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN713

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