Iterative Design Techniques for All-Pole Dual-Bandpass Filters

Two iterative techniques to design all-pole dual-bandpass filters are presented. The oversized aspect of the problem is highlighted and the system is solved by relaxing a parameter, which ensures the convergence. The proposed methods are based on the Remez algorithm and the match points technique. Both methods are applied to design filters by relaxing either a bandpass edge frequency or a ripple level. Also, two examples are presented and demonstrate the speed and accuracy of the proposed techniques.     

全极点高通梯型滤波器的OTA—C实现

本文提出了采用运算跨导放大器(OTA)和电容实现全极点高通滤波器的设计方法,这一方法是基于无源LC梯型网络的节点电压模拟.用OTA综合所有四种阻性终端也予以了考虑.     

Closed-Form Expressions for the Design of Ladder-Type FBAR Filters

Filters based on film bulk acoustic resonators (FBARs) promise to improve the performance of actual filters, however, to the authors' knowledge, their systematic implementation is not straightforward. This letter presents a collection of closed-form expressions for the systematic design of ladder-type filters using FBARs. The procedure is validated against the work of other authors, finding a very good agreement between results     

Bandpass Filters Using Nonlinear FM Surface-Wave Transducers (Short Papers)

A generalized FM method of obtaining bandpass filters using surface-wave delay lines is discussed. Two identical FM transducers are used as input and output. The FM function of the transducers is determined by the required passband.     

Asymmetric Realizations for Dual-Mode Bandpass Filters

Two analytic synthesis techniques are presented for even-degree dual-mode in-line prototype networks up to degree 14. Commencing with the coupling matrix for the double cross-coupled array, rotational transformations are applied to transform the matrix into the form required for the dual-mode in-line asymmetric structure. "Asymmetric" here means that the coupling elements (irises, screws) are unequal in value about the physical center of the filter. The necessity for these asymmetric solutions arose when it was discovered that it was impossible to realize certain useful transmission characteristics with the symmetric in-line structure, on account of their transmission zero pattern in the complex-plane representation of the transfer function. Furthermore, because the full coupling matrix is used instead of the even-mode matrix as with the symmetric solution, the asymmetric in-line realization process may be applied to electrically asymmetric matrices, such as those for single ended filters for multiplexer applications. To demonstrate the validity of the theory, a practical model of each type of realization has been constructed.     

Waveguide Bandpass Filters for Millimeter-Wave Radiometers

A fundamental requirement for most mm-wave heterodyne receivers is the rejection of the input image signal which is located close to the local oscillator frequency. For this purpose we use a bandpass filter, which for heterodyne receivers is also called an image rejection filter. In this paper we present a systematic approach to the design of a waveguide bandpass filter with a passband from 100 to 110 GHz and upper rejection bandwidth in the range from 113 to 145 GHz. We consider two non-tunable filter configurations: the first one is relatively selective with 11 sections (poles) whereas the second one is simpler with 5 sections. We used established design equations to propose an initial guess for the geometries of the filters, optimized the geometries, constructed the filters using two different milling methods, measured their transmission and reflection characteristics, and compared the measurements with numerical simulations. Measurements of both filters agree well with simulations in frequency response and rejection bandwidth. The insertion loss of the 11-pole filter is better than 10 dB and that of the 5-pole filter is better than 5 dB. The 11-pole filter has a sharper attenuation roll-off compared with the 5-pole filter. The upper out-of-band rejection is better than 40 dB up to 145 GHz for the 11-pole filter and up to 155 GHz for the 5-pole filter.     

Synthesis of RC Bandpass Filters

For the first time a method of designing RC bandpass filters is presented. The method consists of two steps. The first step is a scheme to locate the necessary poles and zeros that are RC realizable to produce certain bandpass characteristics. The second step is the synthesis of RC networks to produce these poles and zeros. In the first step, the conformal transformati begin{equation*}s(z) = {left(frac{sn^{2}(z,k) - sn^{2}(alpha{K,k})}{sn^{2}(alpha{K,k})[1 - k^{2}sn^{2}(alpha{K,k})sn^{2}(z,k)]}right)}^{1/2}end{equation*} is used to map the complex frequency s plane into a rectangle in the z plane such that the passband becomes one side, and a part of the negative real axis becomes the opposite side of the rectangle. In the z plane, if poles are located along certain portions of the border and zeros in the interior of the rectangle, certain passband and stopband behavior can be achieved. Among the useful characteristics obtainable by this scheme, the following are three outstanding examples: 1) characteristics that are equal-ripple in the passband and monotonic in the stopband; 2) characteristics that are equal-ripple in the passband and have a number of transmission zeros in the stopband; and 3) characteristics with a maximum gain at the band center and monotonic elsewhere. The steepness of attenuation outside the passband can be altered by a change in the numbers of zeros at the origin and infinity.     

Quarter-Wavelength Side-Coupled Ring Resonator for Bandpass Filters

This paper deals with a dual-mode ring resonator fed by quarter-wavelength side-coupled lines. The resonator synthesis was developed so as to fix the central frequency, bandwidth, and transmission zeros frequencies, as well as the insertion loss in the passband. Based on this resonator, several bandpass filters were designed, which include the cascaded rings and the combination of such ring resonator with coupled line sections. Simulations are proposed throughout the paper to illustrate the various possibilities offered by the concept. The filters' experimental results in microstrip technology are also presented to validate the idea.     

Direct Design Formulas for Asymmetric Bandpass Channel Diplexers

This paper gives direct design formulas for asymmetric bandpass channel diplexers, which allow rapid design of diplexers using narrow-band direct-coupled resonator filters. Computed results for a prototype diplexer are given, and results are presented for a 5.8-GHz asymmetric waveguide diplexer, which demonstrate the high performance possible using this design technique.     

Explicit Design Formulas for Waveguide Single-Sided Filters

Explicit formulas are given for the design of optimum single-sided waveguide filters. Using a uniform waveguide with iris-coupled series stubs irregularly spaced along the waveguide, this class of filter results in a significant reduction in the number of resonators required to meet single-passband and single-stopband specifications over conventional techniques. Design information is given for both the Chebyshev and elliptic function cases from which the required structure may be obtained without recourse to synthesis procedures. Computer simulations of the response characteristics of both the quarter- and modified three-quarter-wave coupled quasi low-pass and the quasi high-pass designs are given. Experimental results on fifth-degree Chebyshev filters operating in X band for the former case are presented showing close agreement with theory.     

一种调试窄带微波带通滤波器的方法

介绍了一种简单、可靠的窄带微波滤波器的调试方法,分析了调试误差,给出了该误差对滤波器性能的影响。     

Development of Packaged Ultra-Wideband Bandpass Filters

In this paper, we present a very compact ultra-wideband (UWB) filter (patent pending), which is integrated in a commercial leaded package. This UWB filter is designed through quasi-equally allocating the first three resonant frequencies of the stub-loaded resonator. Input/output excitation is realized by a technique of wire-bonded interdigital capacitors for obtaining strong wideband coupling. After formulating the resonance conditions and analyzing the characteristics of the stub-loaded resonator, an equivalent-circuit topology is developed and a single-stage prototype is fabricated. Measured results agree well with the results generated from both circuit and full-wave simulations. In order to improve the selectivity, two stages of stub-loaded resonators are cascaded. A two-stage prototype is then assembled in a commercial leaded package and measured with a test fixture. Both simulation and measurement results validate our proposed design methods and packaging solutions. This filter is the first demonstration of integrated UWB filters with a commercial package, which can be conveniently applied in UWB communication and radar systems.      

吸收型准高斯带通滤波器的研制

在数字及高速率信号传输系统中,经常采用Bessel或Gaussian函数滤波器,该类滤波器只有在中心频率(带通滤波器)或DC处(低通滤波器)才有良好的匹配特性,在其他频点都有很大的反射,在微波电路的级联中会产生杂波和干扰。为了解决该问题,设计了一种在通带和阻带内都有很小反射的滤波器,即吸收型(匹配型)准高斯类带通滤波器。介绍了其设计过程及方法,并设计了一种中心频率为100 MHz的吸收型准高斯带通滤波器,给出了仿真结果和实测曲线,实测结果与仿真结果吻合得很好。     

任意阶无漂移全极点有源低通滤波器Schoeffler灵敏度意义上的参数简化

通过对任意阶无漂移全极点有源低通滤波器多参数灵敏度的分析,证明系统总的Schoeffler灵敏度与设计中自由变量的取值无关.并据此导出了该类无漂移有源低通滤波器参数设计的最简形式,使得计算公式大为简化,同时使元件种类减少一半.     

微带SIR带通滤波电路寄生通带的分析

本文分析微带SIR（阶梯阻抗谐振器）带通滤波电路的寄生通带问题。这种滤波器的特点是其寄生响应时以通过阻抗比K进行控制，因而增进了谐波抑制性能。SIR可以采用等电长度或非等电长度。等电长度SIR滤波电路的第三寄生通带的带宽来零，然而，非等电长度SIR滤波电路却增加了设计的灵活性，分析与探讨微带SIR滤波电路的寄生带通问题，对于合理设计与应用这种滤波电路是有益的。     

On the Derivation of the Exact, Closed-Form Capacity Formulas for Receiver-Sided Correlated MIMO Channels

This paper solves the problem of finding a closed-form expression for the average information-theoretic capacity of wireless systems with an arbitrary number of transmitter and receiver antennas. It is assumed that only the receivers have (perfect) knowledge of the channel state and that fading correlation is receiver-sided. The main purpose of the paper is accomplished by introducing a few very simple concepts and performing some clear-cut algebraic manipulations, making the presentation virtually self-contained. The results show a substantial capacity reduction in the presence of correlation between receiver antennas. It is also shown that employing linear arrays with nonuniform spacings may improve the system capacity, and a simple technique to exploit this possibility is presented. Isotropic and nonisotropic propagation scenarios are studied.      

微带阶跃阻抗谐振器小型化滤波器的精确设计

采用具有内部耦合的微带阶跃阻抗谐振器实现小型化,借助电磁场全波分析软件,拟合出了谐振器的级间耦合系数k和外部Q值与谐振器结构的关系曲线,得出了滤波器的物理结构,实际设计制作了一个中心频率为1.52 GHz的带通滤波器,并对滤波器传输特性进行了实测。     

Design Methods for Micro-Electro-Mechanical Bandpass Filters with Transmission Zeros

A design method for high-order electro-mechanical filters allowing the synthesis of architectures of electro-mechanical filters from equivalent electrical prototypes is presented. Conditions for existence of the equivalent mechanical system for a given electrical network are derived. This method is applied to the problem of the design of band-pass electro-mechanical filters with transmission zeros in the stopband. Electro-statical coupling of micro-mechanical resonators that avoids the use of a mechanical coupling spring is introduced. The application to the simulation and design of a bandpass filter with finite transmission zeros implemented in a thick-layer epi-poly silicon micro-machining technology is shown.     

双同轴腔DC-SIR带通滤波器设计

引言 微波滤波器是微波系统中的关键元件,针对不同的应用领域和场合,它可采用多种不同的结构来实现。通常,当滤波器通带的相对带宽大于15％时可以采用交指型结构,大于5％时可以采用梳状型结构,而小于5％时则采用同轴型结构。由于实际项目对滤波器的体积有特殊要求,因而采用g／4的DC—SIR结构。该结构的滤波器具有Q值高、插损小、体积小、带外抑制好以及方便控制杂散谐振频率等优点,可应用于许多场合。     

园杆梳状线微波带通滤波器的研制

给出了一种中心频率为1.675GHz园杆梳状线微波带通滤波器的设计过程.设计方法采用等效电路原理,并用HFSS软件仿真优化.所设计滤波器采用园杆梳状线结构,其结构紧凑,体积小,便于加工.文中将实测曲线和仿真曲线进行了比较,二者吻合很好.