Compact Ultra-Wideband Microstrip/Coplanar Waveguide Bandpass Filter

A novel ultra wideband (UWB) bandpass filter is presented, using a compact coupled microstrip/coplanar waveguide (CPW) structure. The filter comprises of a single CPW quarter-wavelength resonator which is coupled to two microstrip open-circuited stubs on the other side of a common substrate. The two microstrip open-circuited stubs, which are about a quarter-wavelength long at the center frequency, can function as two resonators with associated coupling arrangement to the CPW. This forms a very compact three-pole filter. The proposed filter also exhibits a quasi-elliptic function response, with one finite-frequency transmission zero closer to each side of the passband. Thus, a high selectivity is achieved using a small number of resonators, which leads to low insertion loss and group delay across the passband. The performance is predicated using EM simulations and verified experimentally. The experimental filter shows a fractional bandwidth of 90% at a center frequency of 6.4GHz, with two observable transmission zeros (attenuation poles) at 1.95 and 10.36GHz, respectively. Furthermore, it has a very small size only amounting to 0.25 by 0.08 guided wavelength at the center frequency     

Short-circuited CPW multiple-mode resonator for ultra-wideband (UWB) bandpass filter

An ultra-wideband (UWB: 3.1-10.6 GHz) bandpass filter (BPF) on coplanar waveguide (CPW) is proposed, designed and implemented. A nonuniform CPW multiple-mode resonator with short-circuited ends is constructed and its first three resonant modes are properly allocated around the lower-end, center and higher-end of the specified UWB band. This CPW resonator is then driven at two ends by two parallel-coupled CPW lines with dispersive inductive coupling degree. By properly reallocating the enhanced coupling peak toward the UWB's center, a five-pole CPW BPF with one full-wavelength can be eventually constituted. Its UWB bandpass performance is characterized and optimized on the basis of a simple transmission-line network. Predicted results are confirmed by experiment. Measured results achieve the insertion loss <1.5dB and group delay variation <0.35ns in the realized 3.3 to 10.4GHz UWB passband.     

Ultra-wideband bandpass filter with hybrid microstrip/CPW structure

A novel ultra-wideband (UWB) bandpass filter (BPF) is presented using the hybrid microstrip and coplanar waveguide (CPW) structure. A CPW nonuniform resonator or multiple-mode resonator (MMR) is constructed to produce its first three resonant modes occurring around the lower end, center, and higher end of the UWB band. Then, a microstrip/CPW surface-to-surface coupled line is formed and modeled to allocate the enhanced coupling peak around the center of this UWB band, i.e., 6.85GHz. As such, a five-pole UWB BPF is built up and realized with the passband covering the entire UWB band (3.1-10.6GHz). A predicted frequency response is finally verified by the experiment. In addition, the designed UWB filter, with a single resonator, only occupies one full-wavelength in length or 16.9mm.     

Millimeter-Wave Ultra-Wideband Bandpass Filter Employing Dual-Mode Ring Resonators Fed by Step-Impedance Coupled Lines

This paper presents a novel millimeter-wave ultra-wideband (UWB) bandpass filter (BPF) based on microstrip dual-mode rectangular ring resonators. In order to get strong coupling between the input/output line and the dual-mode ring resonators, a step-impedance parallel-coupled structure is adopted for the design of the filter. On the other hand, transmission zeros are produced by the dual-mode resonator. As a consequence, the filter has low insertion-loss in its passband, sharp attenuation in its lower and upper stopbands and very wide stopbands. As an example, a filter with two dual-mode ring resonators is designed and fabricated. The measured frequency property of the fabricated filter shows good agreement with the simulated response.     

一种新型传输零点可控的微带带通滤波器

提出了一种新型的传输零点可控的微带带通滤波器结构,它由一段低阻抗线和与之相连的平行耦合线构成。通过调节低阻抗线与平行耦合线的偶模阻抗比,可以改变谐振器的2个模式之间的距离,从而灵活的调节滤波器的带宽;而通过调节平行耦合线的间距,则可以方便的调节传输零点的位置。仿真与实测结果都表明该滤波器具有良好的性能：低插损,结构紧凑,可以灵活的调节带宽和传输零点的位置。     

基于QMSIW小型化带通滤波器设计

为有效减小X波段基片集成波导(SIW)滤波器的尺寸和插入损耗,提出了基于四分之一模基片集成波导(QMSIW)和共面波导(CPW)混合结构的小型化带通滤波器。为了提高滤波器的选择性和带外抑制,将两个CPW合并到两个级联的QMSIW谐振器中,由于两个CPW谐振器之间的耦合是电耦合,有助于产生两个传输零点,因而具有较高的选择性。该小型化滤波器尺寸仅为8.1 mm×15.4 mm,中心频率为8.7 GHz,相对带宽是16.1%,仿真测得插入损耗为0.83 dB,带外抑制大于40 dB。     

一种共面波导结构双模方形贴片带通滤波器

提出一种新型共面波导(CPW)结构双模方形贴片带通滤波器。该滤波器采用方形贴片作为谐振器,在方形贴片的两个对称的角上开两个相同的方形切角作为微扰使其简并模式分离并产生耦合,贴片与输入/输出CPW分别设计在介质基板的两个不同的面上。文中给出了该滤波器的结构以及通过仿真和实验获得的性能参数,结果表明该滤波器的通带带宽可在4.9%到7.4%的范围内调节,通带内的最小插入损耗为1.85dB。     

Novel half-mode substrate integrated waveguide bandpass filters using semi-hexagonal resonators

In this paper, a novel bandpass filter is presented, designed, and implemented by using a triple mode semi-hexagonal Half-Mode Substrate Integrated Waveguide (HMSIW) cavity, which has the advantages of compact size, low insertion loss, and high selectivity in upper and lower passband. To realize a triple mode filter, the first resonant mode is shifted to near the next two modes using a via hole perturbation. Two microstrip open stubs connected to open edge of HMSIW resonator are introduced to generate two transmission zeros in the lower passband. The position of transmission zeros could be controlled by adjusting the coupling gap between the microstrip open stub resonators. By etching an E-shape slot on the top plate of HMSIW resonator, two other transmission zeros are produced in the upper passband. A wide-band planar six-pole bandpass filter, which has the advantages of wide bandwidth and small size, is also proposed and fabricated by cascading two triple mode resonators. Measured results indicate that 29% and 47% fractional bandwidth, as well as approximately 1 dB and 1.1 dB insertion loss, are achieved for the proposed filters. Measured results of all those filters agree well with the simulated results.     

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。     

Broadband Cascade Quadruplet Bandpass Filter With Low-Temperature Co-Fired Ceramic Technology

The broadband bandpass filter (BPF) designed with low-temperature co-fired ceramic technology has been proposed in this letter. By adopting a quadruple resonator, the broadband BPF with compact size can be fabricated. A quadruple resonator with metal-insulator-metal capacitors is employed to make inductive and capacitive couplings. The coupling scheme can create two transmission zeros at both sides of passband skirts by appropriately selecting the coupling coefficient. The center frequency and bandwidth ratio of this filter are 3.875 GHz and 50%, respectively. This filter can increase the sensitivity and linearity in the wireless communication system as well     

New compact ultra wideband bandpass filter using modified multi-mode resonator

A new compact ultra wideband (UWB) bandpass filter (BPF) using modified multi-mode resonator (MMR) is presented. The filter consists of a multi-mode resonator with dual spur-lines for providing the dual notch bands at 5.2 and 5.8 GHz and connected with a stepped impedance structure for controlling the transmission zeros at lower and higher passband edge. The interdigital coupling input/output (I/O) lines are used for coupling enhancement. The |S₂₁|-magnitude and the frequencies of notch bands can be well determined by tuning the dimensions of the dual spur-lines. The designed procedures are discussed and good agreement between the measurement and EM simulation are compared.     

Ultra-wideband bandpass filter using back-to-back microstrip-to-CPW transition structure

A novel ultra-wideband bandpass filter is proposed on a back-to-back microstrip-to-CPW transition structure. A multiple-mode resonator on a CPW is formed to allocate its first three resonant modes around the lower-end, centre and upper-end of the 3.1 to 10.6 GHz UWB passband. Its two sides are fed by two microstrip-to-CPW transitions with enhanced frequency-dispersive coupling degree. The designed filter exhibits good UWB passband behaviour with insertion loss <0.5 dB and group delay variation <0.35 ns.     

Dual band notched UWB-BPF based on hybrid microstrip-to-CPW transition

The research paper proposes a compact dual notched band ultra-wideband (UWB) bandpass filter (BPF). The basic architecture of the filter is developed using the hybrid microstrip-to-coplanar waveguide (CPW) technology, wherein a short circuited CPW in ground is coupled vertically via the dielectric to the microstrip lines on the top plane. The broadside alignment generates a three pole BPF with dual transmission zeros (TZs) on either passband/stopband edges which leads to minimum insertion loss passband and sharp roll-offs. Later, multiple spirals and split ring resonators (SRRs) are embedded in the CPW of the UWB filter to introduce the dual notches and widen the stopband respectively. The proposed filter is fabricated to justify its measured response. The proposed filter measures only 14.6 × 7.3 mm².     

一种新颖的微带低通滤波器

提出了一种小型超宽低通微带滤波器的新型结构,即微带与共面波导紧耦合结构。该微带滤波器由接地板上一个共面波导谐振器与基片另一面上开槽的微带结构发生耦合,得到两极点,准椭圆函数响应滤波器,通带上限频率有一个传输零点。该结构有尺寸小、通带损耗小和群时延好等特性。     

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。     

一种新型超宽带带通滤波器的设计

介绍一种新型的超宽带带通滤波器,研究了微带阶梯阻抗谐振器的阻抗特性,利用该并联结构实现了超宽带带通滤波器的带外传输零点。设计了一款性能较好的宽带带通滤波器,实际测试结果与仿真结果十分吻合,证明了设计方法的正确性。     

Ultra wideband bandpass filter with dual-notched bands using stub-loaded rectangular ring multi-mode resonator

This paper presents a new ultra wideband (UWB) bandpass filter (BPF) with dual-notched bands (at 5.2/5.7 GHz) using the stub-loaded rectangular ring multi-mode resonator (MMR). The proposed resonator consists of the dual embedded open-circuited stubs for introducing the dual notch bands and connected with a stub-loaded rectangular ring structure for controlling the two transmission zeros (at 3/11 GHz) at both sides of the UWB passband edge. This study mainly provides a simple method to design a UWB bandpass filter with high passband selectivity and dual-notched bands for satisfying the Federal Communications Commission (FCC-defined) indoor UWB specification. Experimental verification is provided and good agreement has been found between simulation and measurement.     

Analysis and Design of a Chip Filter With Low Insertion Loss and Two Adjustable Transmission Zeros Using 0.18- $mu{hbox{m}}$ CMOS Technology

This paper presents the structure of a high-selectivity bandpass filter that is fabricated on low-resistivity silicon substrate with a commercial CMOS technology. The filter is constructed using crossed coplanar waveguide (CPW) lines and metal–insulator–metal capacitors to ensure that it has the desired passband characteristics. An adjustable capacitor between the input and output ports is employed to form a capacitive cross-coupled path, yielding two transmission zeros in the lower and upper stopbands, respectively. Additionally, the coupling mechanism can be modified by turning on or off the gate of an nMOS transistor to adjust the positions of the transmission zeros by applying an externally controlled voltage. To obtain a low passband loss and to minimize the chip size, high-impedance CPW transmission lines are adopted. Our analysis indicates that the CPW line possesses more advantages than the preferred stacked-ground CPW line for constructing the proposed filter. A very compact $X$ -band experimental prototype with a size of ${hbox{0.88}}times {hbox{0.54}} {hbox{mm}}^{2}$ was designed and fabricated. The measurements reveal an insertion loss of less than 3.2 dB in the passband, which is from 10.6 to 12.7 GHz, and rejection levels greater than 35 dB at the designed frequencies of transmission zeros. Moreover, the lower and upper transmission zeros can be shifted from 5 to 6.5 GHz and from 18 to 21.4 GHz, respectively, by changing the controlled voltage.      

Quadruple-Mode UWB Bandpass Filter With Improved Out-of-Band Rejection

A quadruple-mode ultra-wideband (UWB) bandpass filter with sharp out-of-band rejection is presented in this work. As a starting part of designing a quadruple-mode filter, a mode graph of the initial triple-mode resonator is studied to choose its proper dimensions. Based on these pre-determined dimensions of this triple-mode resonator, two short-circuited stubs are introduced in this resonator to generate two transmission zeros near the lower and upper cut-off frequencies, leading to a higher rejection skirt outside the desired passband. Moreover, as these two stubs are installed, the fourth resonant mode falls down and works together with the first three resonant modes to form a novel quadruple-mode UWB filter. Finally, a filter prototype is designed and fabricated to experimentally validate the attractive in-band and out-of-band performances as predicted in theory.      

Compact Ultra-Wideband Conductor-Backed Coplanar Waveguide Bandpass Filter With a Dual Band-Notched Response

This work presents a novel ultra-wideband (UWB) bandpass filter (BPF) based on a conductor-backed coplanar waveguide structure with tunable transmission zeros. The symmetrical UWB BPF, which consists of the broadside-coupled transitions and the stub resonators in double-layer configuration, achieves a UWB bandwidth with transmission zeros. For characterizing this structure, the equivalent-circuit model is established to realize a four-pole response with two transmission zeros located close to the passband edges. To eliminate the interference of the coexisting wireless local area network (WLAN) within the UWB spectrum, two slotlines are symmetrically arranged on the ground plane of UWB BPF to generate the band-notched frequencies at 5.2 and 5.8 GHz simultaneously. The proposed UWB BPFs have the advantages of compact size, low insertion loss, good selectivity, and flat group delay. All results obtained from the equivalent-circuit model and the full-wave simulation are verified by measurements.