广义切比雪夫型LC滤波器的设计*

提出一种广义切比雪夫型LC滤波器的设计方法,带外传输零点可以是任意设定,其带外特性既可以对称,也可以不对称.采用此方法设计出的LC滤波器,其带内波动可以与最大平坦型滤波器一样很小,而矩形系数可以与椭圆函数型滤波器一样好.每一个传输零点的位置可以由一个元器件的取值大小控制.与椭圆函数型LC滤波器相比,相同数量的元器件,它可以实现更陡的截止特性.     

广义切比雪夫滤波器等效电路参数的提取

通过对等效电路的分析,对广义切比雪夫滤波器各归一化参数的物理意义做了明确的说明,并且,在指定传输零点位置和电路拓扑结构的情况下,采用优化方法,提出了一种灵活有效的提取广义切比雪夫滤波器等效电路参数的方法。最后,用MATLAB编程实现了等效电路参数的自动化提取。     

基于遗传算法与单纯形下山法的广义切比雪夫滤波器的优化设计

广义切比雪夫滤波器是一种高性能滤波器形式,用经典的综合方法提取其参数复杂且难以实现。本文以指定的电路拓扑结构和传输零点作为已知条件,结合遗传算法和单纯形下山法用MATLAB编程实现了一种新的灵活、有效的广义切比雪夫滤波器等效电路参数的优化提取方法。并给出了归一化耦合系数的物理意义及其工程应用系数转换公式。     

Ku 波段微带交叉耦合带通滤波器的结构与设计

基于广义切比雪夫滤波器综合理论,本文设计了一个Ku 波段微带发夹谐振型交叉耦合滤波器。该滤波器的拓扑结构为CQ 型。由于引入非相邻谐振器之间的耦合,在有限频率点处产生传输零点,这样不仅使滤波器具有更好的选择性,而且其结构更加紧凑,尺寸也大大缩小。本文通过HFSS 电磁仿真软件对其进行了优化设计。其仿真结果很好地体现了该滤波器的特性。与同阶数的传统滤波器相比,交叉耦合型滤波器具有更好的带外抑制特性,有较好的工程应用意义。     

四阶交叉耦合广义切比雪夫带通滤波器的设计

利用Matlab和HFSS设计了一个四阶交叉耦合广义切比雪夫滤波器,文中详细介绍了设计步骤,设计出的滤波器中心频率为2.60GHz,通带内的回波损耗为15dB,通带相对带宽FBW=6%,传输零点位置在2.485GHz和2.72GHz。     

切比雪夫Ⅱ型模拟高通滤波器的设计及实现

提出了一种基于反相积分器的信号流图来实现切比雪夫Ⅱ型模拟高通滤波器的方法。首先,基于归一化切比雪夫Ⅱ型模拟低通滤波器极点分布的特点,推导出归一化切比雪夫Ⅱ型模拟低通滤波器零极点和转移函数的公式,得到归一化切比雪夫Ⅱ型模拟低通滤波器设计的步骤;然后,基于频率变换与逆变换,提出一种利用归一化切比雪夫Ⅱ型模拟低通滤波器来设计切比雪夫Ⅱ型模拟高通滤波器的方法;最后,给出了利用归一化切比雪夫Ⅱ型模拟低通滤波器来设计切比雪夫Ⅱ型模拟高通滤波器的实例及其实现电路。     

广义Chebyshev滤波器的优化设计及其快速调试技术研究

文章给出了带传输零点的广义切比雪夫滤波器的分析方法,介绍了优化算法,并讨论了其在滤波器综合设计中的应用,得到耦合矩阵的实际形式。然后对实际微波滤波器的调试技术进行了研究,提出一套人工快速调试方法。最后利用仿真软件建立一个八阶同轴腔滤波器模型并加工调试,实际测试与理论结果吻合较好。     

基于非谐振节点的盒型拓扑结构基片集成波导滤波器设计

针对微波带通滤波器小型化、高性能的应用需求,提出使用单模和双模基片集成波导谐振器相结合设计广义切比雪夫带通滤波器.该结构可实现盒型拓扑结构,并且双模基片集成波导谐振器中的主模TE₁₀₁作为非谐振节点提供一条额外的交叉耦合路径,并能增加一个有限的传输零点;该结构不需要传统负耦合结构就能实现两个有限传输零点,并且该传输零点可以位于通带上方或下方,具有设计灵活的特点.为了进一步提高滤波器的选择性,研究了在四阶滤波器上蚀刻互补开环谐振器设计拓展的盒型拓扑结构滤波器,并实现五阶滤波功能三个有限传输零点.为了验证结构的合理性,设计了两款中心频率为10GHz的对称和非对称响应的四阶滤波器、一款中心频率为5.8GHz的五阶滤波器,并给出相应的含非谐振节点的盒型拓扑结构耦合矩阵进行验证,最后进行加工和测试.耦合矩阵响应、仿真和测试结果一致性较好,表明了该结构设计高性能滤波器的可行性.     

新型高抑制波导滤波器设计

提出了一种新颖的波导带通滤波器设计。该滤波器是一个四阶广义切比雪夫滤波器,中心频率为9.93GHz,带宽为200 MHz,插损小于0.5 dB,带内回波损耗大于20 dB。谐振器为CQ结构,通过一个矩形波导膜片(一个不完全高度的导电杆),实现了交叉耦合,相比传统方法,产生一个额外的传输零点。由于在高端产生了两个零点,使得滤波器在阻带高端10.1 GHz处的带外抑制达到了35 dB以上。仿真实验证明了该设计方法能显著提高滤波器的带外抑制,对滤波器的小型化、高性能化有一定的意义。     

广义Chebyshev滤波器传输零点的确定

传输零点的确定是交叉耦合滤波器综合的最基本要素.本文利用广义Chebyshev函数的极值特性以及滤波器阶数与传输零点最大值的关系,提出了一种根据滤波器特性指标同时确定广义Chebyshev滤波器的阶数和传输零点位置的方法,弥补了传统方法中传输零点确定的人为随意性,在满足技术指标条件下,实现了广义Chebyshev滤波器阶数最少,传输零点位置最佳.几个数值实验显示了该方法的过程和有效性.     

Design of generalized Chebyshev filters with asymmetrically located transmission zeros

A simple design technique is introduced for generalized Chebyshev filters with asymmetrically located transmission zeros. The efficient and exact procedure is given for the calculation of transmission zeros for a class of generalized Chebyshev low-pass prototype filters with a maximum of four asymmetrically located transmission zeros of any multiplicity. This technique is based on obtaining the frequencies of magnitude characteristic extreme values in closed form, and after this, transmission zeros can be calculated by solving a system of nonlinear equations. Novel formulas for orders of zeros of maximally selective filters with equiripple characteristics in the passband and stopband are deduced. The obtained results are verified and illustrated by given examples.     

Maximally selective generalized Chebyshev filters with asymmetrically located transmission zeros

An efficient design procedure for generalized Chebyshev filters with asymmetrically located transmission zeros is presented in this paper. The exact and simple procedure is given for the calculation of transmission zeros, for a class of generalized Chebyshev low-pass prototype filters with a maximum of three asymmetrically located transmission zeros of any multiplicity. This procedure is based on finding the frequencies of magnitude characteristic extreme values in closed form. New formulas for orders of zeros of maximally selective filters with equi-ripple characteristics in the pass-band and stop-band are deduced, and these are very useful in the design procedure. The obtained results are verified and illustrated by corresponding examples.     

Synthèse et réalisation de filtres hyperfréquences à cavités bimodes ayant une réponse en fréquence dissymétrique

This article presents the study and the realization of microwave filters with asymmetric frequency characteristics using dual-mode cylindrical cavities. The synthesis method of such characteristics using generalized Chebyshev transfer functions is described. These functions allow the realization of symmetrically or asymmetrically prescribed transmission zeros. The method consists in synthetizing a generalized low-pass filter, in order to calculate the coupling matrix, the dual-mode structure has to realize. Concerning the practical design of the filter, a method is described for the realization of asymmetric characteristics with dual-mode cavities. Several measured characteristics of different laboratory models are presented.     

Narrow-Band Stripline or Microstrip Filters with Transmission Zeros at Real and Imaginary Frequencies

Simple approximate design equations are derived in this paper for an even degree (n /spl ges/ 6) low-pass inverter capacitance prototype filter having single transmission zeros at both real and imaginary frecuencies. This is achieved by utilizing one or two additional couplings. The transmission zeros improve considerably the passband group delay and increase the skirt selectivity compared to those of the ordinary Chebyshev prototype. An exact and more complicated method based on the known generalized Chebyshev rational function approximation is also presented for the comparison. The prototype with one additional coupling is utilized to realize narrow-bandpass printed circuit filters consisting of half-wave resonators.     

基于LTCC技术的椭圆函数低通滤波器设计

随着无线通信领域的快速发展,人们对微波滤波器性能的要求也越来越高。文章根据滤波器的分类和特点,研究了集总元件滤波器引入传输零点的规律和方法,分析并对比了三种不同类型低通滤波器的衰减特性。根据设计指标要求,基于LTCC技术设计了一款高性能小型化的椭圆函数七阶低通滤波器。滤波器的等效电路包括串联支路中的4个电感和并联支路中的3个LC谐振腔,共10个元件。通过对滤波器模型物理结构的优化,减小了滤波器内部元件间的寄生耦合效应,并在阻带中成功引入了传输零点,改善了滤波器的性能。     

Table-based log-domain linear transformation filter

A design table for realising log-domain linear transformation filters is presented. Based on this design table, doubly terminated LC ladder filters with or without finite transmission zeros can be efficiently synthesised. Moreover, two design procedures are also given. A canonical log-domain elliptic ladder filter can be realised using one of these procedures. Simulation results are given to verify the theoretical analysis     

Microstrip Parallel-Coupled Filters With Cascade Trisection and Quadruplet Responses

Microstrip parallel-coupled filters with generalized Chebyshev responses are presented. The basic structure of the proposed filter is a conventional parallel-coupled filter of which the physical dimensions can be easily obtained by the well-known analytical method. With the aid of the equivalent circuit corresponding to a conventional parallel-coupled filter, the relative insertion phase from source or load to each open end of resonators can be easily obtained by observing the two-port admittance matrix. Applying the cross coupling from source or load to a proper nonadjacent resonator, a trisection or a quadruplet coupling scheme can be realized with prescribed transmission zeros. More importantly, the proposed trisection can be designed to have a transmission zero on the lower or upper stopband by just adjusting the length of the cross-coupling strip. Using the proposed structure, the conventional time-consuming adjusting procedure to obtain initial physical dimensions of filters is no longer required. In this paper, a fourth-order parallel-coupled filter is used as the basic structure to demonstrate various combinations of transmission zeros. Simulated and measured results are well matched.