Quadruple-Mode Coupled-Ring Resonator Bandpass Filter With Quasi-Elliptic Function Passband

Quadruple-mode coupled-ring resonator is used to design quasi-elliptic function bandpass filters (BPFs) with a relatively wide bandwidth. The resonator consists of a pair of coupled rings with two open stubs symmetrically tapped to the inner ring. The stubs are used to move a transmission zero near the center frequency to lower transition band. It is believed that it is the first ring resonator BPF based on the coupled-ring to create four transmission poles and four transmission zeros. Two filters with relative bandwidths of 10% and 15% are fabricated and measured. Good agreement between simulation and measurement is obtained.     

基于枝节加载谐振器的新型三频带通滤波器设计

提出了一种新型平面三频带通滤波器,该滤波器由一个加载短路枝节的阶梯阻抗谐振器,一对加载开路枝节的背靠背E型谐振器,以及包含源负载直接耦合的馈电结构组成.所采用的枝节加载谐振器的多模工作特性使滤波器的体积大大减小,同时每个通带的位置及其耦合特性都能够独立调谐.另外,通过源负载直接耦合引入通带两侧的传输零点,实现了滤波器良好的频率选择性.最后设计并加工了一款高选择性小型化三频带通滤波器,其三个通带的中心频率分别为2.0GHz,3.95GHz和6.35GHz,插入损耗均小于2.5dB,带内回波损耗均优于14dB,实验结果与仿真结果吻合良好.     

An Ultra-Broadband Coplanar-Waveguide Bandpass Filter With Sharp Skirt Selectivity

An ultra-broadband coplanar-waveguide (CPW) bandpass filter (BPF) is demonstrated. The proposed CPW BPF is designed via cascading CPW lowpass and bandpass structures. As compared to the classical CPW BPFs, the ultra broadband is realized relatively easily by separately adjusting the cutoff frequencies of the CPW lowpass and bandpass structures. The cascaded CPW BPF is of greater than 120% 3-dB fractional bandwidth, very sharp skirt selectivity, good stopband rejection, and no repeated passbands     

Design of a New Tri-Band Microstrip BPF Using Combined Quarter-Wavelength SIRs

A new tri-band microstrip bandpass filter (BPF) is designed to produce three passbands at the commercially practical frequencies through a single piece of filter circuitry. The basic component used to build the proposed filter consists of two quarter-wavelength (lambda/4) stepped-impedance resonators (SIRs). One of the lambda/4 SIRs is designed to operate at 1.57 GHz and 5.25 GHz, and the other at 2.45 GHz. The feed positions for the two lambda/4 SIRs are carefully located to have the same distance from the via-hole ground and meanwhile to give the required external quality factors (Q_e's). In such a way, the microstripline sections between the via-hole and each of the feed positions can be combined into one to simplify the filter structure, and to reduce the BPF circuit size. Performance of the newly designed tri-band BPF is verified by measured results     

Wide Stopband Parallel-Coupled Stacked SIRs Bandpass Filters With Open-Stub Lines

In this letter, spurious passband suppression in parallel-coupled stacked stepped-impedance-resonators (SIRs) bandpass filters (BPFs) by means of open-stub lines is proposed and implemented. These filters are composed of parallel-coupled stacked SIRs and open stubs. Moreover, the structure with tapped feeding is employed to create transmission zeros near both sides of the passband skirt. The proposed structure can improve the harmonic suppression so that a wide upper stopband with a satisfactory attenuation level would appear in this BPF. Measured results of the fabricated circuits show that the idea works very well     

一种具有陡峭边带的宽带带通滤波器设计

基于一种新型的多模谐振器设计了一款宽带带通滤波器,该多模谐振器由鱼骨形谐振器及中心加载倒T形谐振器构成。滤波器的中心频率位于2.47 GHz,相对带宽为100%。滤波器具有极高的频率选择性,其边带滚降速度分别为232 dB/GHz和168 dB/GHz。此外,滤波器还具有较低插入损耗0.4 dB,紧凑的电路尺寸以及宽阻带抑制能力。     

A Novel Tri-Band Bandpass Filter Incorporating Stub Loaded Resonator and DGS Resonator

给出了一种采用枝节加载谐振器和缺陷地面结构实现的三通带滤波器。枝节加载谐振器采用 交趾耦合实现了工作于2.45 GHz和5.25 GHz的两个通带,利用缺陷地面结构实现了 工作于3.5 GHz的另一个通带,3个通带实现了独立设计。基于该方法,设制作了一个工 作于2.45 GHz、3.5 GHz和5.25 GHz 3个无线通信频段的三通带滤波器。实测 和仿真结果对比验证了设计方法的有效性。     

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.     

UWB Bandpass Filter Using Microstrip-to-CPW Transition With Broadband Balun

A novel ultra-wideband bandpass filter (BPF) is presented using a back-to-back microstrip-to-coplanar waveguide (CPW) transition employed as the broadband balun structure in this letter. The proposed BPF is based on the electromagnetic coupling between open-circuited microstrip line and short-circuited CPW. The equivalent circuit of half of the filter is used to calculate the input impedance. The broadband microstip-to-CPW transition is designed at the center frequency of 6.85 GHz. The simulated and measured results are shown in this letter.     

新型通带可控低损耗小型四频带通滤波器设计

提出了一种新型通带可控、损耗较低的四频带通滤波器结构。该滤波器的组成采用二阶新型多枝节加载四模谐振器。该谐振器有4 个可单独控制的谐振模式,致使滤波器的中心频率可单独调控,通过控制两谐振器间的耦合系数,滤波器带宽可控。实验结果表明,该滤波器通带可控并满足小型化的要求,4 个通频带中心频率是2.5/3.1/4/5.05GHz,插入损耗为0.1/0.27/0.13/0.16dB,每个通带的回波损耗都优于15dB。实测结果与仿真结果一致。     

基于忆阻器的可切换带通滤波器

将忆阻器作为射频开关,采用传统双模谐振器与改进式短路阶跃阻抗谐振器的组合结构,设计了一款可切换的三频带通滤波器.通过合理设计忆阻器偏置电路的位置,利用忆阻器阻抗的非易失性来实现滤波器通带的可切换功能.当滤波器工作时忆阻器处于断电的记忆状态,从而改善了可切换滤波器的互调性能.文中设计的滤波器拥有四种可切换工作状态,包括三...     

Dual-Band Microstrip Bandpass Filter Using Stepped-Impedance Resonators With New Coupling Schemes

A microstrip bandpass filter using stepped-impedance resonators is designed in low-temperature co-fired ceramic technology for dual-band applications at 2.4 and 5.2 GHz. New coupling schemes are proposed to replace the normal counterparts. It is found that the new coupling scheme for the interstages can enhance the layout compactness of the bandpass filter; while the new coupling scheme at the input and output can improve the performance of the bandpass filter. To validate the design and analysis, a prototype of the bandpass filter was fabricated and measured. It is shown that the measured and simulated performances are in good agreement. The prototype of the bandpass filter achieved insertion loss of 1.25 and 1.87 dB,$ S_11$of$-$29 and$-$40 dB, and bandwidth of 21% and 12.7% at 2.4 and 5.2 GHz, respectively. The bandpass filter is further studied for a single-package solution of dual-band radio transceivers. The bandpass filter is, therefore, integrated into a ceramic ball grid array package. The integration is analyzed with an emphasis on the connection of the bandpass filter to the antenna and to the transceiver die.     

Photonic Microwave Bandpass Filter With Negative Coefficients Using a Polarization Modulator

A novel photonic microwave bandpass filter with negative coefficients implemented using a polarization modulator (PolM) is proposed and experimentally demonstrated. In the proposed filter, a lightwave from a tunable laser source (TLS) is sent to a PolM, with the incident lightwave adjusted to have its polarization direction aligned at an angle of plusmn45deg to the principal axes of the PolM. A microwave signal is applied to the PolM through its RF port. Thanks to the polarization modulation in the PolM, two complementary microwave signals with identical amplitudes carried by two optical carriers with orthogonal polarizations are generated. The two complementary optical microwave signals are then sent to an optical delay line consisting of one section or two sections of polarization-maintaining fiber (PMF), with the polarization directions aligned with the fast and slow axes of the PMF. A photonic microwave bandpass filter with two or four taps is obtained     

Bandpass Filter Using Substrate Integrated Waveguide Cavity Loaded With Dielectric Rod

A novel bandpass filter (BPF) is designed using the substrate integrated waveguide cavity loaded with a dielectric rod. The resonant frequencies and unloaded Q-factor are determined by a set of analytical equations. Using the technique of dielectric loading, the proposed BPF has the advantages of compactness, good spurious suppression characteristics, low insertion loss, and low cost, which is demonstrated by good agreement between the simulated and measured S-parameters.      

C-Band Multilayer Bandpass Filter Using Open-Loop Resonators With Floating Metallic Patches

This letter presents a fourth-order quasi elliptic bandpass filter based on a multilayer technology. Thanks to the use of the third dimension, multilayer technology appears as a very convenient solution when a high coupling is required. This led us to use a coupling coefficient-based approach to design a very compact filter through the association of open-loop resonators and floating metallic patches to elevate coupling.     

Wideband Bandpass Filter With Reconfigurable Bandwidth

this letter proposes a novel building block for developing tunable wideband bandpass filters. The proposed circuit block mainly consists of short circuit coupled lines and short circuit stubs with pin diodes as tuning elements. This work aims to demonstrate reconfigurable bandwidth of this type of filter. Two filters are designed and fabricated; one can be switched between a fractional bandwidth (FBW) of 16.3% and 35% at a center frequency of 1.9 GHz, and the other can be switched from a FBW of 27.8% to 37.4% at a center frequency of 1.9 GHz. The insertion loss and return loss in the first filter range from 4.17 dB to 0.4 dB and 27.54 dB to 19.04 dB. The second filter exhibits an insertion loss ranging from 0.73 dB to 0.43 dB and a return loss range from 31.1 dB to 27.7 dB. The tested filters show good agreement with EM simulations.      

A UWB Bandpass Filter With Two Transmission Zeros Using a Single Stub With CMRC

A compact bandpass filter is proposed for lower-band ultra-wideband applications. It entails the design concept of a stub-tapped half-wavelength line resonator which provides three transmission poles in the passband and two transmission zeros at the high and low rejection bands. The two stubs are replaced by a single dual-band stub and the parallel coupled-line structures are meandered, leading to a compact size of 0.26lambda_g by 0.32lambda _g     

Compact Dual Band Bandpass Filter Using Novel E-Type Resonators With Controllable Bandwidths

A compact microstrip dual band bandpass filter (BPF) using novel E-type resonators is presented in this letter. The E-type resonator is a short-circuited stub loaded hairpin resonator, two passband frequencies of which can be regulated by adjusting the characteristic impedance and electrical length of the hairpin and the stub. By combining pseudo-interdigital coupling structure, the coupling coefficients of two bands can be adjusted to a desired value in a relatively wide range. In addition, hook feed line is introduced to obtain desired external coupling degrees for two bands. Thus, controllable fractional bandwidths (FBWs) can be achieved. Two two-order 2.45/5.25 GHz dual band BPFs with 3 dB FBW 7%/7% and 5%/5%, respectively, are designed. The measured result agrees well with the simulation.      

A Bandpass Filter Design Using Half-Wavelength Stepped Impedance Resonators With Internal Couplings

We propose a new type of microstrip half-wavelength$(lambda/hbox2)$stepped impedance resonator (SIR) for use in bandpass filter (BPF) designs. This$lambda/hbox2$SIR has an internal coupling section that can be used to generate a coupling coefficient in the filter design in addition to couplings between SIRs. It also contains additional stepped impedance lines that shift and suppress the lowest even-mode resonance frequencies to more than what can be achieved by conventional$lambda/hbox2$SIRs. Moreover, a transmission zero is generated close to its fundamental resonance frequency$(f_0)$which can be used in definition of the filter response. A fourth-order microstrip BPF with 10% bandwidth was constructed using two of the proposed$lambda/hbox2$SIRs with a stepped impedance ratio$(R)$of 0.528. The experimental result shows that the filter can achieve low in-band loss and out-of-band attenuation of 52.6dB up to$hbox3f_0$. The lowest spurious resonance frequency is shifted to$hbox3f_0$as opposed to 2.5$f_0$in conventional$lambda/hbox2$SIRs with the same$R$value.     

Dual-Band Filter Design With Flexible Passband Frequency and Bandwidth Selections

In this paper, improved dual-band filter design is studied. The dual-band resonators are composed of shunt open- and short-circuited stubs. In order to fulfil the requirements of dual-band inverters, a structure of stepped-impedance asymmetric coupled lines is proposed and its equivalent circuit is also derived. The dual-band filter is then designed based on this equivalent circuit. This type of filter can achieve relatively large practical passband center frequency ratios (in theory infinite), and it has more freedom of bandwidth ratio. The circuit size is also reduced. Detailed design procedure is presented and, finally, a filter example is given to validate the theoretical study