基于圆头谐振器的低插损带通滤波器设计

针对插入损耗高和选择性低等问题,提出了一种具有圆形开路终端的新型谐振器拓扑结构。该结构将传统的U型发夹滤波器改成V型,在V型结构的终端引入圆形开路谐振器,并在开路枝节短截线上过孔。基于新型谐振器结构设计了一款尺寸为42.9 mm×36.54 mm (0.35λ_g×0.3λ_g)的带通滤波器。该滤波器具有插入损耗低、通带可控和远端优良等优点,并且采用新型谐振器之间的交叉耦合,在近端1 GHz附近产生一个传输零点,有效优化了阻带抑制和带通滤波器的选择性。仿真结果表明,带通滤波器的中心频率为1.7 GHz, 3 dB的相对带宽为20%,最大回波损耗优于30 dB,最小插入损耗为0.20 dB,左边的带外抑制在50 dB以下,右边的带外抑制优于20 dB。实物测试结果与仿真结果基本一致,整体性能偏好,证明了该结构的可行性。     

改进型3IDT-LCR结构的低损耗小矩形系数SAW滤波器

通过理论仿真,该文研制了一种改进型的3IDT-LCR结构,并基于该结构在42°Y-X LiTaO₃压电基片上研制出一种低损耗、小矩形系数的SAW滤波器。滤波器标称频率为253.75 MHz,实测插入损耗1.05 dB,低端带外抑制接近80 dB,高端带外抑制接近65 dB,-1 dB带宽10.52 MHz,-3 dB带宽12.54 MHz,-40 dB带宽16.68 MHz,矩形系数1.33。实测结果表明,该改进型3IDT-LCR结构的SAW滤波器具备低插入损耗、小矩形系数和高带外抑制的特点。     

柔性人工表面等离激元传输线的小型化设计

为了实现高集成度通信系统中高频信号的可靠传输,提出了一种小型化叉指H形人工表面等离激元传输线结构. 采用共面双导体形式,并在金属矩形凹槽处添加叉指结构,实现色散特性调控和尺寸缩减. 同时给出单元结构的等效电路模型,验证了小型化结构的设计原理,分析了力学形变时传输线的性能. 仿真与测试结果表明,与常规的人工表面等离激元相比,叉指H形人工表面等离激元传输线可在保持相同带宽（3～15.25 GHz）的同时,线宽减少79.5%,尺寸仅为2.28λ_g×0.098λ_g（λ_g为中心频率对应的波长）. 在平坦和变形时加工实物的带宽保持在3～12.90 GHz,与仿真结果较吻合. 设计的结构具有高频、小型化和柔性超薄等特点,在超小型高速通信系统中具有潜在的应用前景.     

具有陷波特性的UWB带通滤波器设计

基于复合左右手传输线理论,设计了一款新型超宽带(UWB)带通滤波器。该滤波器结构简单且尺寸只有0.288λg×0.105λg(4.58 mm×12.62 mm)。通带为2.9~10.75 GHz,3 d B,10 d B分数带宽分别为115%,153.8%,通带内插入损耗小于0.5 d B,回波损耗小于–16.5 d B,边带抑制能力为–31.5 d B。为了抑制WLAN信号对超宽带通信系统的干扰,利用加载短截线谐振器的方法对该滤波器进行了陷波处理,陷波深度大于20 d B。滤波器实物测试与仿真结果相吻合,能应用于超宽带通信系统中。     

基于CMOS的新型人工表面等离激元滤波器设计

本文基于0.18μm CMOS工艺提出了一种新型微波人工表面等离激元(Spoof Surface Plasmon Polariton,SSPP)耦合式滤波器结构并进行加工和测量，同时设计了一种太赫兹SSPP四边形滤波器并进行了全波仿真.新型微波SSPP耦合式滤波器通带为11～12.3 GHz(S₁₁<-10 d B,S₂₁>-3.5 d B)，结构紧凑，电尺寸仅为0.018 4λ_g×0.008 4λ_g，远小于其他基于集成电路工艺设计的无源滤波器.通过优化与调整，可以将新型微波SSPP耦合式滤波器的性能进一步优化到要求范围内.太赫兹SSPP四边形滤波器通带为210.8～241.3 GHz(S₁₁<-10 d B,S₂₁>-4.7 d B)，带内插入损耗仅为2.7 d B，带外抑制良好.两种SSPP滤波器均采用非接触式电磁耦合的新型能量传递方式，结构设计新颖，并且微波段SSPP耦合式滤波器小型化优势明显，电尺寸仅为0.019λ_...     

一种中心枝节折叠的新型超宽带滤波器

为了改善超宽带滤波器存在插入损耗较大,带外抑制特性较差等问题。采用中心加载折叠枝节多模谐振器结构,设计了一种新型超宽带滤波器。改变该滤波器多模谐振器的参数,可调节谐振器的谐振频率。该滤波器整体性能良好,具有结构紧凑,尺寸小,插入损耗小及带外抑制特性好等优点。仿真结果表明,该滤波器的中心频率为6.85GHz,通带为3¹0.7GHz,实现相对带宽112%。实物测试结果与仿真结果基本一致。     

基于耦合传输线多陷波超宽带滤波器的设计

为滤除窄带信号对超宽带通信系统的干扰,提出了一款具有多陷波特性的超宽带滤波器。采用λ/4平行耦合线构造结构紧凑的滤波单元节,并通过单元节级联的方式实现三陷波特性。将扇形枝节接入短路枝节匹配线,有效抑制了高次谐波。将环形谐振腔引入带阻单元,获得了良好的矩形系数。该滤波器的体积仅为25. 5 mm×49.9 mm×0. 6 mm,结构紧凑。仿真结果显示:滤波器的工作带宽为3 ~10 GHz,三个陷波频段为3. 5 ~3. 6 GHz、5. 7~5. 9 GHz 和7. 9 ~8. 1 GHz,有效滤除了WiMAX(3. 3 ~3. 6 GHz)、WLAN(5. 7 ~5. 8 GHz)以及X 波段卫星通信系统(7.9 ~8.4 GHz)的干扰。该滤波器通带内插入损耗较小且带外谐波抑制良好,抗干扰能力强,适用于各种超宽带系统。     

基于EMSIW结构和QMSIW结构的紧凑型滤波器设计

为有效减小S波段基片集成波导SIW( Substrate Integrated Waveguide)滤波器的尺寸和插入损耗，提出了一种基于 1/4模基片集成波导QMSIW(Quarter Mode Substrate Integrated Waveguide)和1/8模基片集成波导EMSIW(Eighth Mode Substrate Integrated Waveguide)的紧凑型带通滤波器，利用EMSIW与QMSIW谐振腔体结构互补的特点，减少电磁泄露，改善插入损耗，通过设计交叉耦合，实现传输零点的引入，以改善其选择性和带外抑制水平，分别设计了四腔体EMSIW小型化带通滤波器以及EMSIW-QMSIW结构的小型化带通滤波器，其中心频率均为3.8ＧＨｚ，两滤波器的相对带宽为13.8％和8.4％，测试插入损耗均小于1.05ｄＢ，带外抑制高于60ｄＢ，传输零点数均为3，且标准化尺寸仅分别为0.24λ０×0.11λ０和0.35λ０× 0.12λ０。?     

基于缺陷地面结构的超宽带微带滤波器的设计

针对传统的超宽带滤波器存在陷波深度不足的问题,基于新型缺陷地面结构和加载枝节的方法设计了一款超宽带滤波器.该结构通过内嵌、折叠开路枝节来形成双陷波带,在保证尺寸紧凑的同时实现了对陷波的需求.为了保证陷波深度,在超宽带滤波器两端加载了不对称倒T型枝节.通过刻蚀新型缺陷地面结构来增强带外抑制特性以及陷波深度.该滤波器工作频...     

低插损高频SAW滤波器的研究

采用单层膜、梯形结构基于128°YX-LiNbO₃材料研究了Al电极厚度、叉指占空比、反射栅周期、拓扑结构对插损、带外抑制和矩形度的影响。为了降低带内波动和插入损耗,该文设计了一种叉指换能器(IDT)型反射栅结构,该结构对采取优化措施前后谐振器的带内最大尖峰损耗分别降低了8.84%和0.55%。最后采用此反射栅结构设计了一款低插损高频声表面波(SAW)滤波器,有限元仿真结果表明,该滤波器的中心频率为2.520 5 GHz,插入损耗为-0.502 12 dB,带外抑制大于30 dB,-3 dB损耗带宽大于98 MHz。     

L波段双层交指线性相位MEMS滤波器的设计

针对射频MEMS滤波器的带外抑制能力较差和带内群延时不平坦的问题,设计了一种窄带宽、低插损、高选择性的L波段射频MEMS线性相位滤波器.选取高介电常数的衬底材料实现窄带传输,采用双层交指结构的谐振器实现线性相位,减小了电路体积.利用HFSS软件对滤波器的性能进行优化.结果表明,该滤波器的中心频率为1.46 GHz,带内...     

一种IPD吸收式低通滤波器的设计

为解决反射信号损害系统性能的问题,提出了一种具有高带外抑制和高带外吸收的小型化吸收式低通滤波器。该滤波器通过高通通路和低通通路实现了吸收式低通滤波器;通过抑制增益支路实现了高带外抑制。利用ADS和HFSS仿真软件对滤波器结构进行优化设计,并进行了实物的加工和测试。实测结果表明:该滤波器的3 dB截止频率为4 GHz,其带内最小插入损耗0.88 dB,通带内DC到3.5 GHz的回波损耗大于20 dB,阻带回波损耗大于10 dB,10.5 GHz处的阻带抑制大于45dB,从8 GHz到30 GHz的带外抑制大于33 dB,实测结果与仿真结果有较好的吻合。该滤波器尺寸仅为1220μm×650μm×87.71μm,相比传统PCB、LTCC工艺的滤波器,体积大大缩小,符合现代射频与微波系统小型化的发展趋势。     

一种L波段多层低群延时滤波器设计

针对目前L波段滤波器体积大、群延时高、损耗大等问题,提出了一种L波段多层低群延时滤波器。通过选取高硅基作为衬底材料,采用多层交指结构的谐振器来降低带内群延时,减小体积。利用HFSS软件对滤波器展开建模与仿真。通过调整谐振器的参数,得到最佳设计方案。仿真结果表明,该滤波器的中心频率为1.5 GHz,带内插入损耗小于1.2 dB,带内群延时波动小于500 ps,在中心频率左右0.3 GHz处的带外抑制达到50 dB,滤波器尺寸较小,为8 mm×7 mm×1.5 mm。     

Scattering matrix approach for the design of microwave filters

A synthesis procedure, based on a distributed parameter model, for the design of microwave filters is presented in this paper. The frequency response of the filter is described in terms of the characteristic polynomial T₂₁=S₁₁/S₂₁ where S₁₁ and S₂₁ are the scattering parameters of the filter. Starting from the desired polynomial T₂₁, the design scheme directly yields the scattering parameters of the various junctions, which can be realized by any kind of discontinuity. The capability of synthesizing an arbitrary frequency response allows one to introduce the concept of a “predistorted” characteristic polynomial in order to compensate for the degradations caused by multimodal interactions, frequency dispersion, etc. Comparison with measured data of a Chebyshev-like eight-pole E-plane filter confirms the validity of the method also in the presence of losses     

Nested input-constrained codes

An input-constrained channel, or simply a constraint, is a set S of words that is generated by a finite labeled directed graph. An encoder for S maps, in a lossless manner, sequences of unconstrained input blocks into sequences of channel blocks, the latter sequences being words of S. In most applications, the encoders are finite-state machines and, thus, presented by state diagrams. In the special case where the state diagram of the encoder is (output) deterministic, only the current encoder state and the current channel block are needed for the decoding of the current input block. In this work, the problem of designing coding schemes that can serve two constraints simultaneously is considered. Specifically, given two constraints S₁ and S ₂ such that S₁⊆S₂ and two described rates, conditions are provided for the existence of respective deterministic finite-state encoders ε₁ and ε₂ , at the given rates, such that (the state diagram of) ε₁ is a subgraph of ε₂ Such encoders are referred to as nested encoders. The provided conditions are also constructive in that they imply an algorithm for finding such encoders when they exist. The nesting structure allows to decode ε₁ while using the decoder of ε₂. Developments in optical recording suggest a potential application that can take a significant advantage of nested encoders     

具有带外抑制特性的Ka波段低功耗低噪声放大器

基于0.15μm GaAs赝配高电子迁移率晶体管(PHEMT)工艺,成功研制了一款30~34 GHz频带内具有带外抑制特性的低功耗低噪声放大器(LNA)微波单片集成电路(MMIC)。该MMIC集成了滤波器和LNA,其中滤波器采用陷波器结构,可实现较低的插入损耗和较好的带外抑制特性;LNA采用单电源和电流复用结构,实现较高的增益和较低的功耗。测试结果表明,该MMIC芯片在30~34 GHz频带内,增益大于28 dB,噪声系数小于2.8 dB,功耗小于60 mW,在17~19 GHz频带内带外抑制比小于-35 dBc。芯片尺寸为2.40 mm×1.00 mm。该LNA MMIC可应用于毫米波T/R系统中。     

Universal three input and one output current-mode filter withoutexternal passive elements

A new current-mode universal filter is proposed. The filter uses only operational amplifiers and operational transconductance amplifiers (OTAs) and can realise lowpass, highpass, bandpass, notch and allpass responses without changing circuit topology. The parameters ω₀, ω₀/Q₀, and the gain can be electronically tuned by adjusting the bias currents of the OTAs. The proposed circuit has low sensitivity     

Integrated metal magnetic film coupled line circulators for monolithic microwaveintegrated circuits

A new structure of integrated planar metal magnetic film coupled line (MMFCL) circulators is presented, in which a metal magnetic film is used instead of ferrite materials. Simulation was performed with HFSS based on coupled-mode theory. An insertion loss of 4 dB and isolation of -13.5 dB between S₂₁ and S₁₂ over a frequency band of 3 GHz (from 36.5 to 39.5 GHz) were realised for a three-port MMFCL circulator     

A 12-Pole Narrowband Highly Selective High-Temperature Superconducting Filter for the Application in the Third-Generation Wireless Communications

An ultra-selective high-temperature superconducting bandpass filter was designed and fabricated to satisfy the demands of the third-generation wireless communications. This filter was designed to have 12-pole quasi-elliptic response with 4.68-MHz bandwidth in the third-generation communications band (a fractional bandwidth of 0.0023). Full-wave simulations were conducted by using Sonnet software. A novel, compact, and low radiation resonator with a high-quality (Q) factor value was developed to reduce the parasitical coupling. In order to satisfy the demand of high band-edge steepness, three pairs of transmission zeros at finite frequencies were introduced in the cascaded quadruplet coupling structure. The filter was fabricated on a 2-in-diameter 0.43-mm-thick sapphire wafer with double-sided YBCO films. The measurements showed that the passband center frequency (f₀) of the filter is 2.038 GHz at 67 K with a midband insertion loss of 0.67 dB and the return loss better than 15 dB. The measured response of the filter also exhibited ultra-high band-edge steepness of 140-220 dB/MHz. Better than 60 dB of out-of-band rejections for frequencies very close to the band edge (|f-f₀|>2.7 MHz), better than 90 dB at frequencies 7.5 MHz away from the center frequency and up to 100 dB of wideband rejections were achieved