Design of Dielectric Waveguide Bandpass Filters Using Parallel-Coupled Gratings

Techniques for the design of narrow-band (of the order of a percent or so), bandpass filters using dielectric waveguide gratings are presented. These filters use both single, uncoupled gratings and parallel-coupled configurations of gratings to form multiresonator bandpass filter structures. Transmission-line equivalent circuits are used to model the dielectric waveguide gratings. Using this model, it is then shown how direct-coupled-resonator theory can be applied to such filter structures to synthesize a prescribed passband having Chebyshev or maximally flat characteristic. On the other hand, the parallel-coupled gratings give these filters broad and strong, absorptive stopbands, as is explained. Experimental results are presented which show good agreement between theoretical and measured results.     

Low Phase-Noise Planar Oscillators Employing Elliptic-Response Bandpass Filters

In this paper, a low phase-noise planar oscillator employing an elliptic bandpass filter as a frequency stabilization element within its feedback loop is presented. The oscillator phase noise is significantly reduced by taking advantage of the group-delay peaks formed at the passband edges of the elliptic filter. A filter optimization technique for low phase-noise oscillator designs is introduced and applied to a four-pole bandpass elliptic filter. An $X$-band oscillator using the optimized filter in the feedback loop is designed and tested. At the oscillation frequency of 8.05 GHz, the measured phase noise is $-$143.5 dBc/Hz at 1-MHz offset frequency. The oscillator exhibits an output power of 3.5 dBm with an dc–RF efficiency of 10%. To the authors' best knowledge, this is the lowest phase noise performance for an $X$-band planar microwave oscillator.      

Microwave Bandpass Filters Containing High-Q Dielectric Resonators

This paper is concerned with dielectric disks used as resonators in microwave bandpass filters. For many years it has been known that modes of resonance occur in isolated dielectric bodies having air boundaries, and that very compact high-Q resonators can be achieved when /spl epsiv/ /sub r/, is high and tan /spl delta/ is low. High-purity TiO/sub 2/ ceramic material, for example, has an /spl epsiv/ /sub r/ about 100, tan /spl delta/ about 0.0001, and Q/sub u/ about 10 000. Practical applications of dielectric resonators have previously been limited by insufficient design information. Formulas are derived for the coupling coefficient between adjacent dielectric-disk resonators within a metal waveguide below cutoff. This metal enclosure is necessary for shielding and to prevent radiation loss. Comparisons between theoretical and experimental coupling coefficient values show very good agreement in each of the three bandpass configurations treated in this paper. Techniques of loop and probe coupling to the end resonators of a multiresonator bandpass filter are discussed and methods of supporting the resonators are suggested. The conclusion is made that microwave dielectric resonators offer important size reductions compared to conventional resonators of similar high Q, but that the center-frequency change of the dielectric resonators as a function of temperature is excessive for many applications. Temperature stabilization is one solution, but preferably a material should be developed having electrical characteristics similar to TiO/sub 2/ ceramic, but with at least an order of magnitude improvement in temperature sensitivity.     

A Miniature High-Q Bandpass Filter Employing Dielectric Resonators

The miniaturization of high-Q resonant microwave structures is of great importance. This must he done to keep pace with the size reduction of other related components. The need has led to an investigation into the feasibility of using dielectric materials as microwave resonators. This paper deals with the application of the TiO/sub 2/ dielectric resonator in a narrowband bandpass filter operating in the 2200 to 2300 MHz telemetry band. The study confirms the theory that a bandpass filter employing dielectric resonators is practical to build, is compact, and will approach the performance of an equivalent waveguide filter. The design employed five resonators mounted in a cylindrical tube that was 1.4 inches in diameter by 4.3 inches long and weighed 4.6 ounces. An equivalent waveguide filter would be approximately 2.3x4.5x16 inches long and would weigh approximately 64 ounces (WR-430). The thermal sensitivity of the dielectric resonator employing TiO/sub 2/ is an inherent problem and oven regulation for narrowband applications will be required. Small, inexpensive thermal jackets are available that will control the filter stability to a value equal to, or better than, that obtained with a filter utilizing aluminum cavities operating in a typical uncontrolled temperature environment.     

Design and Performance of Coplanar Waveguide Bandpass Filters

End-coupled resonator bandpass filters built in coplanar waveguide are investigated. The admittance inverter parameters of the coupling gaps between resonant sections are deduced from experiment, and bandpass filter design rules are developed. This allows easy filter synthesis from "prototype" low-pass designs. Measurements of single section resonator quality factors are used to predict filter insertion losses. Several examples of filters realized in coplanar waveguide are presented. Odd-mode coplanar waveguide filter elements that shortcircuit the even coplanar waveguide mode are investigated. Filter tuning, accomplished by adjusting the height of conducting planes above the resonant filter sections, is demonstrated.     

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.     

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。     

圆杆交指型滤波器的设计

介绍了圆杆交指型带通滤波器的设计原理和方法,根据交指滤波器的设计理论获得圆杆的自电容和互电容,利用计算机辅助设计工具进行数值计算,结合图表得到滤波器的最初尺寸。给出了一个中心频率为830 MHz圆杆交指滤波器的设计过程,利用HFSS软件仿真,提高了设计效率和精度,仿真结果和理论结果吻合良好,证明了设计方法的可行性。     

一种抽头式交指带通滤波器的设计及实现

传统的交指带通滤波器设计采用公式计算归一化自电容和互电容,并通过查表计算得到滤波器的参数,该方法计算繁琐,且计算误差较大.文中介绍了一种根据谐振器的直接耦合原理,利用两终端的外部品质因数Q和谐振器间的耦合系数K设计抽头式交指型带通滤波器的方法.据此,设计了一种用于微波选频的交指滤波器,借助ADS软件对滤波器进行仿真和优化.通过仿真及实测结果的分析对比,进一步给出了设计改进方案.     

源与负载感性交叉耦合的小型介质滤波器

为了提高滤波器的阻带衰减,研究了源与负载感性交叉耦合的小型介质滤波器。首次提出一种新概念：将源和负载看作准谐振器。以贴片电感作为源与负载之间、源与第二个谐振器之间的交叉耦合元件,两个准谐振器和两个介质谐振器可构成级联四节(CQ),一个准谐振器和两个介质谐振器可构成级联三节(CT)。分析了传输零点的位置,详细讨论了这种滤波器结构的设计方法。采用介电常数为80的介质陶瓷组装了3个两级介质滤波器,并进行测试,结果表明传输零点的个数和位置与仿真设计相符合。滤波器的体积小,均为14 mm×6.5 mm×10 mm。     

运算跨导放大器(OTA)椭圆高通滤波器设计

本文提出了OTA椭圆高通滤波器的设计方法。基于无源RLC高通梯型网络的节点电压模拟,系统地生成了由三类网络和五种接阻终端组合构成的所有可能的OTA高通滤波器结构。     

平行耦合微带线带通滤波器的多步法优化设计

提出一种通过提升设计频率来解决平行耦合微带带通滤波器中边缘场效应导致的中心频率偏移的方法。同时分析了导致这种偏移的原因,并阐述了该方法的理论基础。给出的实例证明,在使用微波软件设计平行耦合微带线带通滤波器时,这种方法是简洁且可行的。     

Employing Open/Short Via-Hole to Control the Coupling Coefficient for LTCC Bandpass Filters

In this letter, the multilayered bandpass filter (BPF) is synthesized with the assistance of via-holes. By controlling the coupling coefficient with open or short via-hole, the transmission zero can be shifted to lower or higher passband skirt. Theoretical analysis and design procedures are provided. The prototypical low-temperature co-fired ceramic BPFs are fabricated and measured as well. In addition, comparisons of simulated results and experimental data are shown. Good match validates the proposed filter.      

新颖的对数域电流模式二阶低通带通滤波器设计

文中利用指数跨导元件，运用状态空间综合方法，设计了新颖的对数域电流模式二阶低通，带通滤波器。所提出的滤波器电路结构简单，具有很好的高频性能，适合于低电压工作，其截止频率由参考偏置电流控制，调节范围很宽。电路由双极型晶体管和接地电容构成，适合于全集成实现。ＰＳＰＩＣＥ仿真表明，所提出的电路是可行的。     

双模方形带通滤波器的分析、建模及设计

本文报道一种利用谐振器中缺口位置设计双模带通滤波器的新方法.用这种方法既可以实现具有一对传输零点的双模带通滤波器,也可以实现无传输零点的双模带通滤波器.通过分析缺口位置对谐振器内电场模式分布的影响,建立了双模滤波器的拓扑结构图.利用全波仿真软件,基于不同的缺口位置设计了中心频率为2.05GHz,带宽为100MHz的两种...     

Design of Dual-Band Bandpass Filters Using Stub-Loaded Open-Loop Resonators

In this paper, open-loop resonators loaded by shunt open stubs are proposed to design compact dual-band bandpass filters with improved out-of-band rejection characteristics. The second passband of the dual-band filter is obtained by tuning higher resonant modes of the open-loop resonator by the stub length and position. A tapped-line input/output feed structure is used for external coupling. Required external coupling is obtained by adjusting the tapping position and dimension of the stub-loaded resonator. A lossless transmission line model is used to determine the resonance properties of the resonator and the external quality factor. Theoretical predictions are verified by the experimental results of three dual-band filters.     

耦合二次节型开关电流带通滤波器的改进双线性设计

本文采用改进双线性变换，以一种新型双二次节为基块进行开关电流（ＳＩ）带通滤波器的设计。这种双二次节是用本文提出的双抽样方式ＳＩ改进型通用积分器构成的。文中介绍了耦合二次节型全极点及有限传输零点带通滤波器的设计方法。用该方法设计的ＳＩ滤波电路具有较好的高频特性，并能保持无源原型的低灵敏度特点。文中给出了Ｃｈｅｂｙｓｈｅｖ和Ｅｌｌｉｐｔｉｃ带通滤波器设计的实例。     

一种新颖微带双通带带通滤波器的设计方法

本文提出了一种新颖的微带双通带带通滤波器的设计方法。该微带双通带滤波器由两个中心频率不同的滤波器组成,并采用耦合线实现外部耦合。设计中引入源与负载之间的耦合,得到了额外的有限频率传输零点,改善了滤波器的衰减特性。通过调节源与负载之间耦合的强弱,可以适当地调节传输零点的位置。经设计并加工了一款4阶微带开环结构双通带滤波器,实测响应与仿真响应吻合较好,验证了该方法的有效性。     

Design of Compact Tri-Band Bandpass Filters Using Assembled Resonators

A novel approach for designing tri-band bandpass filters with independently controllable center frequencies and improved stopband rejection characteristic is presented in this paper. The assembled resonator constructed by a stepped impedance resonator and a common half-wavelength resonator is employed to obtain tri-band response. The stepped impedance resonator is designed to operate at the first and third passbands and the other resonator is designed to operate at the second passband. Two kinds of filter configurations with cascaded and pseudointerdigital formats are proposed. Based on lossless lumped-element equivalent circuit, it is found that both filter structures can introduce transmission zeros between passbands. To verify the proposed approach, two filters are designed and fabricated, the measured results exhibit tri-band bandpass responses with high selectivity.