A novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using SICMRC

This paper presents a novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using stepped-impedance resonator and bended transmission line structure. The filter includes stepped-impedance prototype filter and stepped-impedance compact microstrip resonator cells that are combined in one structure. The proposed filter has good specifications such as sharp roll-off, ultra-wide stopband and low insertion loss. The transition band is approximately 0.25 GHz from 1.75 to 2 GHz with corresponding attenuation levels of ?3 and ?40 dB. The attenuation level in the stopband is better than ?20 dB that is achieved from 1.94 to 23 GHz, and the insertion loss in the passband is less than 0.4 dB. The proposed filter is fabricated and measured, and the simulation and measurement results are found to be in good agreement with each other.     

Compact microstrip lowpass filter with wide stopband and sharp roll-off using tapered resonator

In this article, a novel microstrip lowpass filter (LPF) with specifications such as sharp cut-off, wide stopband, low insertion loss and high return loss using tapered resonator is presented. The LPF has cut-off frequency of 1.11 GHz, where unwanted harmonics are suppressed by novel tapered cells. The bandwidth is enhanced, and the size is reduced as compared to the conventional tapered filter. The transition band is approximately 0.29 GHz from 1.11 to 1.4 GHz with corresponding attenuation levels of –3 and –20 dB, respectively. The stopband with greater than –20 dB rejection is from 1.4 to 8.9 GHz, insertion loss in the passband is less than 0.1 dB, return loss is less than –18 dB and the overall size of the filter is 0.12 × 0.073 λ_g. The proposed filter is fabricated and measured. The simulation and measurement results are in good agreement. This LPF is designed for microwave communication applications, especially wireless video transmitters.     

Compact UWB Bandpass Filter Using Stub-Loaded Multiple-Mode Resonator

A compact microstrip-line ultra-wideband (UWB) bandpass filter (BPF) using the proposed stub-loaded multiple-mode resonator (MMR) is presented. This MMR is formed by loading three open-ended stubs in shunt to a simple stepped-impedance resonator in center and two symmetrical locations, respectively. By properly adjusting the lengths of these stubs, the first four resonant modes of this MMR can be evenly allocated within the 3.1-to-10.6 GHz UWB band while the fifth resonant frequency is raised above 15.0GHz. It results in the formulation of a novel UWB BPF with compact-size and widened upper-stopband by incorporating this MMR with two interdigital parallel-coupled feed lines. Simulated and measured results are found in good agreement with each other, showing improved UWB bandpass behaviors with the insertion loss lower than 0.8dB, return loss higher than 14.3dB, and maximum group delay variation less than 0.64ns in the realized UWB passband     

Design and analysis of a super compact wide-band bandpass filter based on metamaterial resonators

In this paper, a novel compact wide-band bandpass filter (BPF) with a wide frequency range is presented. This filter consisting of a multi-mode resonator (MMR) and four metamaterial unit-cells benefits from a very compact size. Unit-cells based on a complementary spiral resonator (CSR) including a metallic via, improve both upper and lower stopband rejection and compensate the insertion loss (I.L) within the passband altogether. This wide-band filter presents a 3-dB bandwidth of 7.7 GHz, ranging from 3 GHz to 10.7 GHz and the Insertion loss is less than 0.7 dB over the passband. The measured results are in good agreement with both the full-wave electromagnetic simulation and the proposed circuit model results. The dimension of the fabricated filter is 0.128 λ × 0.1 λ (i.e., 5.6 × 4.4 mm²). This filter is considerably compact compared to the other wide-band bandpass filters with the same substrate.     

Dual mode wideband band-pass filter with notched band for communication system

This paper presents a planar microstrip wideband dual mode Band-Pass Filter (BPF) from 2 GHz to 3.4 GHz with a notched band at 2.62 GHz. The dual mode band-pass filter consists of a ring resonator with two quarter-wavelength open-circuited stubs at ?? =90° and ?? =0°, respectively. A square perturbation stub has been put at the corner of the ring resonator to increase the narrow stopbands and improve the performance of selectivity. By using a parallel-coupled feed line, a narrow notched band is introduced at the required frequency and its Fractional BandWidth (FBW) is about 5%. The proposed filter has a narrow notched band and a wide pass-band with a sharp cutoff frequency characteristic, the attenuation rate for the sharp cutoff frequency responses is 297.17 dB/GHz (calculated from 1.959 GHz with ?34.43 dB to 2.065 GHz with ?2.93 dB) and 228.10 dB/GHz (calculated from 3.395 GHz with ?2.873 dB to 3.507 GHz with ?28.42 dB). This filter has the advantages of good insertion loss in both operating bands and two rejections of greater than 16 dB in the range of 1.59 GHz to 1.99 GHz and 3.49 GHz to 3.98 GHz. Having been presented in this article, the measurement results agree well with the simulation results, which validates our idea.     

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.     

基于微带线-槽线转换的具有陷波特性的超宽带带通滤波器

利用阶跃阻抗槽线多模谐振器和微带线与槽线的信号转换,设计了一款具有陷波功能的超宽带带通滤波器。滤波器在一块介质基板上制作而成,基板接地面上有一条终端短路宽度不均匀（阶跃阻抗）槽线谐振器,基板的另一面有两条与槽线谐振器垂直的“L”形的开路微带线,作为滤波器的信号输入和输出端口,在这两端口的附近各刻有一条“U”形的槽线,以实现滤波器的陷波功能。仿真和实测表明了滤波器的工作带宽可达3.2GHz-11.4GHz,其中陷波带宽为5.2GHz-5.75GHz。     

Compact wide stopband lowpass filter using spiral loaded tapered compact microstrip resonator cell

A new spiral loaded tapered compact microstrip resonator cell (SPLT-CMRC) is presented. The addition of spiral stubs to the CMRC creates transmission zeroes in the stopband which extended the stopband of the ?lter. The proposed resonator is used to design a compact lowpass ?lter (LPF) with wide and high rejection in stopband. The fabricated ?lter has a 3 dB cutoff frequency at 8 GHz. The insertion loss in the passband is less than 0.2 dB from DC to 7.2 GHz. The proposed ?lter has wide stopband from 9.47 to 40 GHz with attenuation level of ?20 dB. The demonstrated filter is designed and fabricated. There is a good agreement between the measured and simulated S-parameters.     

Small Ultra-Wideband (UWB) Bandpass Filter With Notched Band

A compact ultra-wideband (UWB) bandpass filter (BPF) with notched band has been proposed and implemented in this letter. H-shaped slot is studied and adopted to tighten the coupling of inter-digital capacitor in order to improve the BPF's performance. Three pairs of tapered defected ground structures (DGS) are formed to assign their transmission zeros towards the out of band signal, thereby suppressing the spurious passband. Combining these two structures we obtain a small sized UWB BPF. Meander line slot is developed to reject the undesired wireless local-area network (WLAN) radio signals. An experimental UWB filter with notched band was fabricated with 35% less length as compared to an embedded open-circuited stub. The measured BPF insertion loss is less than 1.0 dB throughout the pass band of 2.8 to 10.8 GHz, the variation of group delay less than 0.20 ns in this band except for the notched band, and a wide stopband bandwidth with 20 dB attenuation up to at least 20.0 GHz.     

Dual and tri-band bandpass filters based on novel Π-shaped resonator

A novel Π-shaped resonator is proposed, and compact dual-band and tri-band bandpass filters that meet IEEE 802.11 application requirements by using the new resonator are designed. The dual-band bandpass filter centres at 2.45 and 5.6 GHz with a simulated passband insertion loss of no more than 0.8 dB, and the tri-band bandpass filter which is got by two-path coupling achieves simulated passband insertion loss of no more than 1.1 dB. The new designs are demonstrated by experiment. The new filters have advantages of simple and compact structures, low passband insertion losses, good frequency selectivity and miniature circuit sizes. All these have prospect to be applied in future wireless communication systems.     

Tri-Band Bandpass Filter With Sharp Passband Skirts Designed Using Tri-Section SIRs

This letter presents a second-order tri-band bandpass filter (BPF) designed using tri-section stepped-impedance resonators (TSSIRs). The impedance ratios of the TSSIRs were computed using the formulas expressed as functions of the passband center frequencies, which are located at 1.57, 2.45, and 3.5 GHz. A cross-coupled configuration was arranged to sharpen the passband skirts. The newly designed tri-band BPF was verified by circuit implementation and very good agreement between the simulated and measured results was observed.     

一种新型超宽带带通滤波器的设计

针对超宽带(UWB)系统易受无线网络信号干扰及传统的超宽带带通滤波器阻带较窄,不能有效抑制谐波的问题,提出了一种新型的UWB带通滤波器,该滤波器由两级交指梳状耦合谐振器级联组成,通过增加耦合指的个数来实现陷波特性,然后在两个交指谐振器的中间添加一个槽线锥形谐振器,使该滤波器具有抑制高次谐波特性,达到拓宽高阻带的效果,同时由于槽线谐振器的加入,陷波频段的抑制电平进一步提高.实验结果证明,所设计的滤波器既能保证3.1～10.6 GHz频段内的插入损耗小于3 dB,陷波频段为5.7～5.8 GHz,陷波频段的抑制电平高达-43 dB,同时又能拓宽高频阻带.     

EBG-Embedded Multiple-Mode Resonator for UWB Bandpass Filter With Improved Upper-Stopband Performance

An electromagnetic bandgap (EBG) embedded multiple-mode resonator (MMR) is proposed to constitute an upper-stopband-improved and size-miniaturized ultra-wideband (UWB) bandpass filter (BPF). This EBG-embedded MMR is studied to relocate its first three resonant modes within the 3.1-10.6GHz passband, whereas placing its 4th resonant mode at the coupling transmission zero of interdigital coupled-lines that drive this MMR at two sides. Meanwhile, the fifth resonant mode is rejected by virtue of the bandstop behavior of the EBG itself. Thus, a modified UWB BPF with widened upper-stopband, sharpened upper rejection skirt and lowered loss in the passband is finally constituted, designed and fabricated. The measured results demonstrate that the insertion loss is lower than 1.0 dB in the passband (4.0-10.6GHz) and higher than 15.0dB in the upper-stopband (12.0 to 20.0GHz) while the group delay variation in the passband is less than 0.2ns     

70 GHz Folded Loop Dual-Mode Bandpass Filter Fabricated Using 0.18 $mu$ m Standard CMOS Technology

This letter presents the design and implementation of a 70 GHz millimeter-wave compact folded loop dual-mode on-chip bandpass filter (BPF) using a 0.18 $mu$m standard CMOS process. A compact BPF, consisting of such a planar ring resonator structure having dual transmission zeros was fabricated and designed. The size of the designed filter is 650$,times,$ 670 $mu$ m$^{2}$ . Calculated circuit model, EM simulated and measured results of the proposed filter operating at 70 GHz are shown in a good agreement and have good performance. The filter has a 3-dB bandwidth of about 18 GHz at the center frequency of 70 GHz. The measured insertion loss of the passband is about 3.6 dB and the return loss is better than 10 dB within the passband.      

基于方开环谐振器的双陷波超宽带滤波器

针对超宽带系统易受窄带信号干扰的问题,设计了一种可以抑制无线局域网络(WLAN)和卫星通信信号干扰的双陷波超宽带带通滤波器。该滤波器的主要谐振结构由T型枝节加载的多模谐振器组成,改进的T型枝节增加了两个传输零点,同时减小了滤波器尺寸;通过耦合方开环谐振器,实现了两个陷波特性,调节谐振器尺寸,可以得到所需的陷波频率。测试结果表明,该滤波器的尺寸仅16.7mm×8.5mm,中心频率为6.9GHz,通带为3.0~10.8GHz,陷波中心频率在5.8GHz和8.04GHz,衰减最低点分别为-27dB和-18dB,仿真与测量结果有较好的一致性。     

Design of the Compact Wideband Bandpass Filter With Low Loss, High Selectivity and Wide Stopband

In this letter, a novel compact wideband bandpass filter using the asymmetric stepped-impedance resonator (SIR) with one step discontinuity is designed and implemented to achieve characteristics of low loss, wide stopband and very high passband selectivity, simultaneously. The first two resonant modes of the asymmetric SIR are coupled together and applied to create a wide passband. The design procedure is discussed in detail. The proposed filter at center frequency ${rm f}_{0}$ of 4 GHz has very good measured characteristics including a low insertion loss of 0.5 $pm$ 0.3 dB, the bandwidth of 2.9–5.3 GHz, sharp rejection due to two transmission zeros in the passband edge. Experimental results of the fabricated filter show a good agreement with the predict results.      

一种共面波导结构双模圆环带通滤波器

提出了一种新型的用共面波导馈线结构实现的双模圆环带通滤波器。该滤波器采用传统的圆环作为谐振器,引入阶梯阻抗作为微扰使其简并模式分离并产生耦合。这样的微扰结构我们称之为环形阶跃阻抗谐振器,它与输入/输出共面波导分别设计在介质基片的两个不同的面上。文中给出了该滤波器的结构及通过仿真和实验获得的性能参数,结果表明该滤波器在带宽为11.4%时通带内的最小插损为1.42dB。     

A microstrip wideband bandpass filter based on λ/2 stub with spurious passband suppression scheme

In the design of bandpass filters, the use of λ/2 stubs of shunt configuration had been mostly unacceptable due to their effect of narrow stopband bandwidths in the ensuing filters. The design of bandpass filter presented in this article introduces 360° series transmission line segments to increase the stopband bandwidths to an acceptable level without affecting the wide passband. This designed filter has low insertion loss of less than –1.98 dB and a fractional bandwidth of 50% at 6 GHz mid-band frequency. A sharp rejection in the stopband is observed. To further widen the bandwidth of stopbands, a series capacitor and a shunt stub are used. The transmission line model of the filter is in good agreement with measured results. The filter is planar and is fabricated on FR-4 substrate which makes it cost-effective and easy to fabricate.     

Q-Band GaAs Bandpass Filter Designs for ALMA Band-1

We report on the design and experimental results of Q-band GaAs bandpass filters (BPFs) for the Atacama Large Millimeter/submillimeter Array (ALMA) band-1 receiver. The BPF is required to reject the lower side band from 15.3 to 29 GHz while retain minimum insertion loss across the passband of 31.3 to 45 GHz. In order to reduce the size and weight of receiver module effectively, on-chip BPF designs using the commercial GaAs process are proposed. The parallel-coupled BPF with quarter-wavelength resonators is adopted to achieve a wide fractional bandwidth of about 37%. In addition, the capacitive/inductive loaded coupled-line and the stepped-impedance resonator are used to largely reduce the filter size. Moreover, the cross-coupling effect is introduced to create transmission zeros, such that the required 25 dB stopband rejection below 29 GHz can be achieved. Specifically, two GaAs BPFs with sizes less than $1.24times 0.8 {rm mm}^{2}$ are demonstrated. They will be applied to the multi-chip-module version of ALMA band-1 receiver prototype for further system evaluation and feasibility studies.      

Design of the Compact Dual-Band Bandpass Filter With High Isolation for GPS/WLAN Applications

In this letter, a novel compact dual-band bandpass filter (BPF) is designed to achieve the characteristic of low insertion loss and high isolation for global position system (GPS)/wireless local area network (WLAN) applications. This BPF is implemented by properly selecting the impedance ratio (R) and physical length ratio $(alpha)$ of the asymmetric stepped-impedance resonator (SIR) with one step discontinuity. The coupling coefficient between the coupled asymmetric SIRs is calculated by using full-wave simulator IE3D. The proposed filter has very good measured characteristics including a low insertion loss of 1.1 dB for both passbands, a high isolation insertion loss of 55 dB between the two passbands and a wide stopband rejection of 38 dB from 2.7 to 5.3 GHz. Good agreement with responses of electromagnetic (EM) simulation and measurement is compared.