基于混合梳状线谐振器的三阶恒定带宽电调微带滤波器研究

文章提出了一种基于终端加载变容管的混合型梳状线谐振器的三阶电调微带带通滤波器,仅采用两个电压源进行控制．根据奇偶模分析方法,推导了混合梳状线谐振器间耦合系数计算公式,通过合理设计级间及输入输出耦合结构,绝对带宽保持恒定的要求可以得到满足．设计了一个调谐范围为1.0GHz～1.78GHz ,3dB绝对带宽为104.5±8MHz的三阶电调滤波器,其插入损耗小于5.7dB ,回波损耗优于16dB ,对二次谐波的抑制达到60dB ．实验结果表明,测试结果与电磁仿真结果基本一致．     

频率可调带通-带阻可切换滤波器的设计

该文设计了一种频率可调带通与带阻可切换微带滤波器,在距λ/2(λ为波长)谐振器开路端约1/4处加载变容二极管实现中心频率可调,利用PIN二极管实现带通与带阻两种状态的可切换。通过对耦合系数与外部品质因数(Q)值的分析,选取合适的参数可实现滤波器绝对带宽在调谐范围内保持恒定。带通状态时,由于源与负载间的耦合及谐振器间的混合电磁耦合,在滤波器的通带两侧各产生1个传输零点,提高了滤波器的选择性与阻带抑制。选用介电常数2.2的F4BM介质基板制作实物并用矢量网络分析仪进行测量。测量结果表明,当PIN管加正偏压,变容二极管加反偏压时,实现了中心频率可调的带阻滤波器;当PIN管不加偏压,变容二极管加反偏压时,实现了中心频率可调的带通滤波器。滤波器的中心频率调谐范围为3.45～3.90 GHz,调谐范围内绝对带宽保持恒定。该滤波器尺寸为44.4 mm×16.1 mm(0.59λ_g×0.21λ_g)(λ_g为调谐范围中心频率对应波长),符合小型化要求。     

变容管调谐微带环形谐振器带通滤波器的研究

本文研究了变容管调谐的微带环形谐振器带通滤波器。给出了微带环形谐振器的谐振特性和两环形谐振器间的耦合特性。制作了二级变容管调谐微带环形谐振器的带通滤波器，实验结果和理论吻合较好。     

一种X波段梳状线可调带通滤波器

设计了一款X波段压控可调梳状线带通滤波器,通过调整加载变容二极管的偏置电压改变电容值大小,从而达到调整滤波器中心频率的目的。根据恒定带宽条件对滤波器耦合系数以及外部Q值的要求,确定梳状线滤波器的尺寸参数,并对其进行电磁仿真优化,最终制作的X波段可调滤波器尺寸为16 mm?20 mm?21 mm,控制电压7.6~15.4 V,实现滤波器中心频率8~10 GHz连续可调。在调谐频率范围内,滤波器通带宽度15%,回波损耗小于–10 dB,矩形系数小于2.8。     

同址干扰用电调谐带通滤波器设计

介绍了电调谐滤波器设计原理及在同址干扰中的应用,采用伪梳状线思想对传统结构滤波器进行优化,提出两端均为电容调谐的电调滤波器结构。设计微带线实现的变容管电调谐带通滤波器,对改进后的滤波器性能进行仿真。该文设计的滤波器调节范围为580~900 MHz,在体积上具有一定优势。     

压电换能器电调介质滤波器的设计与实现

为了解决变容管电调窄带滤波器的插入损耗大和承受功率小的问题,研究了用压电换能器作电调元件的电调介质滤波器.分析了压电换能器调谐介质谐振器的机理,讨论了耦合系数和外部Q值的控制方法,仿真结果表明耦合系数和外部Q值随调谐频率的变化较小.采用HFSS软件设计和优化了两级电调介质滤波器的结构,并用高Q值的介质谐振器制作了两级电调介质滤波器.根据ANSYS软件的分析结果,提出了提高电调率的有效措施.当控制电压为0~50V时,滤波器的中心频率调谐范围为4.155~4.205GHz,3dB带宽为37~40MHz.     

基于波纹耦合微带线的可调谐带通滤波器

设计了一种紧凑5阶双零点可调谐带通滤波器。通过在传统梳状线滤波器中引入波纹耦合微带线结构,该滤波器可以在中心频率调谐过程中保持绝对带宽恒定,同时尺寸相较于传统方法可减小50%。谐振器中引入分布式补偿电容利于滤波器应用于高介电常数衬底的微带线结构。基于源与负载间的耦合,引入两个传输零点来提高滤波器的衰减特性。HFSS仿真结果显示,当加载的电容值为2.43 pF时,滤波器的中心频率为1.48 GHz,带宽为194 MHz,插入损耗为1.36 dB。随着加载电容值从2.15 pF增加到2.93 pF,滤波器的中心频率从1.55 GHz减小至1.37 GHz。保持绝对带宽恒定的情况下,通带内的插入损耗小于1.5 dB。     

基于λ/4和非对称λ/2谐振器的三阶微带滤波器设计

提出了一种基于电容加载 λ/4 梳状线谐振器和电容加载非对称 λ/2准梳状线谐振器的三阶耦合滤波器拓扑结构。利用奇偶模方法,给出并分析了整个滤波器结构的等效电路,由导纳矩阵可以得出传输零点的位置。实际制作了一个中心频率为1.83 GHz的三阶微带带通滤波器,相对带宽为9%,带内中心插损仅为1.45 dB,回波损耗优于14 dB。传输响应在通带两侧分别存在一个传输零点,有利于提高滤波器的选择性。实验结果表明,测试结果与仿真结果基本一致。     

基于双模谐振器的双通带可调谐滤波器设计

从理论上分析了开路支节加载双频谐振器的谐振模式,通过在谐振器末端加载变容二极管的方式,设计了一款双通带独立可调谐滤波器。通过调节谐振器末端变容二极管电容值大小来改变通带的中心频率,通过调节支节末端的变容二极管来调节通带的带宽。该滤波器的两个通带之间相互独立,调谐其中一个通带对另一个通带几乎没有影响。通过引入源与负载的耦合,使得双通带两侧各产生一个传输零点,提高了滤波器的选择性和带外抑制能力。最终设计出的滤波器第一通带的中心频率在1.08~1.19 GHz之间连续可调,绝对带宽在112~152 MHz之间连续可调;第二通带中心频率在2.07~2.22 GHz 之间连续可调,其绝对带宽在132~189 MHz 之间连续可调。在调谐过程中,通过调节中心开路支节末端变容二极管加载直流电压大小,实现调谐过程两通带带宽基本维持不变。     

数控电调带通滤波器的设计与制作

设计了一种新型电调谐带通滤波器,研究了数字信号控制滤波器电调谐的技术。采用数模转换器和高压运放实现数字信号与直流电压的转换;以变容二极管作为调谐元件;带通滤波器采用梳状微带线结构,并给出了结构参数。最后制作了一个由8位二进制编码控制的电调谐带通滤波器,其中心频率在300～1200MHz可调。测试结果与理论设计基本吻合。     

Electronically Tunable Microwave Bandpass Filters

Combline filters with novel input and output coupling networks which enable broad-band tuning to be achieved with minimum degradation in passband performance are discussed. Explicit design formulas for these filters are presented. Computer analysis of varactor tuned combine bandpass filters including the small signal varactor equivalent circuit is presented enabling filter performance to be easily evaluated. The design and experimental performance of a varactor tuned combline filter, realized in suspended substrate stripline is described. This filter toned from 3.2 GHz to 4.9 GHz exhibited low passband insertion loss and its performance was is close agreement with theoretical expectations.     

Progress of a tunable active bandpass filter

A review of a tunable active bandpass filter developed in our research group is given here. Presented first is the basic structure of an end-coupled microstrip-line bandpass filter. Next discussed is the concept of using coupled negative resistance to compensate the loss of tank circuit. Then, the method of using varactor diode or mesfet varactor to tune the center frequency of the passband is discussed. The capability of optical-control of mesfet varactor and the concept of using mesfets as three-terminal varactors are also discussed.     

Varactor-tuned combline bandpass filter using step-impedance microstrip lines

In this paper, a varactor-tuned combline bandpass filter using step-impedance microstrip lines is considered so that the absolute passband bandwidth can be maintained nearly constant within the tuning range. The difference between the odd- and even-mode characteristics of the coupled microstrip line makes it difficult to design a tunable bandpass filter with minimum degradation in passband performance. By using step-impedance microstrip lines, couplings between resonators can be controlled so that the constant bandwidth requirement could be satisfied with reasonable design parameter values. Lumped inductors are used for input and output coupling networks. Design equations are derived, and experimental results are compared with theoretical ones based on these equations.     

一种具有可重构陷波功能的差分宽带带通滤波器

文章提出了一种具有陷波可重构功能的差分宽带带通滤波器,具有良好的差模响应与共模抑制效果。所设计的差分带通滤波器通过采用对称的四阶分支线结构,在差模激励下可等效出电壁,在共模激励下可等效出磁壁。同时,该滤波器通过对称地耦合两个1/4波长的阶梯阻抗谐振器来产生所需频段的陷波特性,并通过改变阶梯阻抗谐振器上变容二极管两端的直流偏置电压来改变阶梯阻抗谐振器的电长度,从而调整陷波的频段。仿真和测试结果表明该差分带通滤波器的工作频带为2.7~7.3 GHz,相对阻抗带宽为92%。在工作频段中,差模回波损耗均大于10 dB,共模抑制大于15 dB。随着变容二极管两端直流控制电压从10.3 V变化到3.6 V,陷波的中心频率从5.6 GHz移动到6.1 GHz,同时滤波器宽带带通特性基本保持不变。     

Novel Centrally Loaded Resonators and Their Applications to Bandpass Filters

This paper presents several novel centrally loaded resonators and their applications to various types of bandpass filters. Based on the theoretical analysis, it is found that the even- mode resonance of the proposed resonators can be conveniently controlled without affecting the responses at the odd-mode resonant frequencies. Benefiting from this feature, the resonator can be utilized to design not only harmonic-suppressed bandpass filters and dual-band bandpass filters but also tunable bandpass filters. The tunable filter offers a fixed passband and a tunable one. The center frequency of the upper passband can be electrically tuned, whereas the performance of the lower one is maintained constant. To demonstrate these applications, four filters using the proposed resonators are implemented. The experiments verify the theoretical predictions and simulations.     

一种毫米波调谐微带滤波器的研制

该文基于金丝键合工艺和薄膜工艺,实现了一种低插损、小型化毫米波调谐微带滤波器。首先提出了一种加载矩形孔的半波长开路可调谐振器,通过在不同矩形孔上键合金丝来改变谐振器的等效电感值,从而改变谐振频率。然后利用所提出的可调谐振器实现了一种Ka频段五阶调谐带通滤波器,通过改变键合金丝状态来调谐频率,实现仿真和实测结果之间的偏差修正,解决了在毫米波频段由于介电常数批次性差异以及加工误差等因素造成的窄带滤波器频率偏移的问题。为了验证其可行性,对五阶调谐微带滤波器进行仿真、优化、加工及测试。结果表明,该滤波器的通带可调范围为35.35~35.95 GHz,插入损耗小于4.6 dB,能够实现所需通带。     

A Novel Crossed Resonator and Its Applications to Bandpass Filters

A novel open and short stubs loaded crossed resonator and its applications to cross-coupling filter and tri-band bandpass filters are presented in this paper. Based on the lossless transmission line model analysis, it is found that the first three resonance frequencies of the crossed resonator can be conveniently controlled. Benefiting from this feature, the resonator can be utilized to design not only a cascaded triplet (CT) filter, but also a tri-band bandpass filter. The tri-band filter offers two tunable passbands and one fixed passband. The first and third passband frequencies can be tuned effectively by changing the lengths of the stubs. To demonstrate these applications, a CT filter and two tri-band bandpass filters using a crossed resonator are implemented. The experiments verify the theoretical predictions and simulations.      

Varactor-tuned active bandpass filter with low noise performance

An active tunable bandpass filter based upon the negative resistance method using a microstrip combline network is presented. The negative resistance is realised using a common-drain series feedback structure. 0.4 octave tuning with significant improvement in passband performance was achieved and the noise performance was comparable with its passive counterpart.