Design of new quadruplexer with compact size,high isolation and wide stopband

This study presents a quadruplexer (1.8/2.4/3.5/5.8 GHz) with compact size, high isolation, low insertion loss and wide stopband based on the multi-mode resonators. The quadruplexer is composed of four pairs of coupled multi-mode resonators (uniform impedance resonator, UIR and stepped impedance resonators, SIRs) and the source–load coupling lines. Each channel (passband) can be easily determined by tuning the impedance ratio (K) and length ratio (α) of the SIRs so as to implement a 2-order bandpass filter individually. The source–load coupling lines are designed to correspond to the quarter-wavelength of the center frequency at each channel. The proposed quadruplexer shows a simple configuration, an effective design method and a small circuit size.     

双频带通滤波器的优化设计

利用阶跃阻抗谐振器优化,设计了一个工作在无线局域网(2.4/5.2GHz)的双频带通滤波器。通过奇、偶模分析,在阶跃阻抗谐振器理论计算公式基础上,根据不同的阻抗比条件,阶跃阻抗谐振器谐振频率比与阶跃阻抗高、低阻抗电长度之比的关系曲线,可以方便地确定阶跃阻抗谐振器的谐振频率和电长度,通过sonnet电路仿真软件验证了设计的合理性,并给出了用于无线通信2.4、5.2 GHz双频带通滤波器的设计结果。该带通滤波器可以分别在2.4、5.2 GHz处得到较好的通带性。由于交叉耦合的存在,该双频带通滤波器在两个通带端各有一个传输零点,以此来提高滤波器的通带频率选择性。最后,测量结果与仿真结果基本吻合。     

Miniaturized dual-band bandpass filter with good frequency selectivity using SIR and DGS

A miniaturized dual-band bandpass filter (BPF) using stepped impedance resonator (SIR) and defected ground structure (DGS) is presented. In order to get two desired passbands, two different transmission paths and source–load cross coupling have been implemented. One path is the SIR, and the other is the DGS. Meanwhile, it is easy to obtain good frequency selectivity by introducing several transmission zeros. The coupling scheme and current distributions are applied to demonstrate the flexible design approach. A dual-band BPF is designed, simulated, and fabricated to demonstrate the performance of the proposed dual-band filter. The measured results show that the fabricated dual-band BPF has two passbands centered at 2.41 and 3.52 GHz with the fractional bandwidth of 5.8 and 7.7%, respectively. The measured insertion loss is about 2 dB and 2.2 dB at the lower and upper passbands. The measured results show good agreement with the simulated ones.     

Microstrip dual-band bandpass filter with independently tunable passbands using varactor-tuned stub loaded resonators

In this paper, a dualband bandpass filter with independently tunable passband is proposed. Two half-wavelength resonators with shunt stub have been placed side by side, fed with a common input-output microstrip line to achieve the individual tunability without affecting other passband. For tuning resonance frequency, varactor diodes are used at the ends of the half wavelength resonators and also at the end of the shunt stubs. Proper shunt stub length and width are derived numerically in such a way that only one control voltage is required in each passband. Measured results show that lower passband can be tuned in a frequency range from 1.78 to 1.96 GHz, whereas the upper passband varies from 2.27 to 2.39 GHz individually. H shaped DGS is integrated below the input-output feed lines to suppress higher order harmonics up to 21 GHz with more than 19 dB attenuation.     

基于CQ拓扑的三通带滤波器的设计

提出和设计了一个三通带带通滤波器,采用CQ拓扑和缺陷地结构,产生了8个传输零点,获得了高频率选择和带间隔离。半波长阶梯阻抗谐振器(SIR)设计为同时谐振在第1、2和3通带的公共谐振器,公共谐振器和分别谐振在第1、3通带的1/4波长谐振器(QWR)组合构成CQ拓扑结构。同时,阴刻在地表面的缺陷地结构提高了调节耦合系数的自由度,便于调节耦合系数来满足特定要求。设计、加工和测量了工作在2.4GHz、3.4GHz和5.5GHz的三通带滤波器,测试结果和仿真结果的一致性证明了提出的设计方法的可靠性。     

基于SRR-DGS 新型高选择性带通滤波器的设计

通过在阶梯阻抗谐振器(Stepped Impedance Resonators, SIR)上加载开口谐振环缺陷地结构(Split- Ring Resonator Defected Ground Structure, SRR-DGS),设计了一款具有高选择性和较好带外抑制性能的带通滤波器。 测试结果表明,该滤波器的3 dB 工作频带为2. 56 ~2. 77 GHz (7. 9%),带内最大插入损耗为0. 8 dB。此外,在通带 两侧各有两个传输零点,分别位于2. 17 GHz、2. 48 GHz、2. 86 GHz 和3. 81 GHz,带外抑制均大于30 dB,表明该滤波 器具有较好的带外抑制特性。同时,仿真与测试结果吻合较好,验证了该滤波器设计方法的有效性。     

Compact multilayer dual-band bandpass filter design using stepped impedance resonators

Compact dual-band bandpass filter (BPF) for the 5th generation mobile communication technology (5G) radio frequency (RF) front-end applications was presented based on multilayer stepped impedance resonators (SIRs). The multilayer dual-band SIR BPF can achieve high selectivity and four transmission zeros (TZs) near the passband edges by the quarter-wavelength tri-section SIRs. The multilayer dual-band SIR BPF is fabricated on a 3-layer FR-4 substrate with a compact dimension of 5.5 mm ×5.0 mm ×1.2 mm. The measured two passbands of themultilayer dual-band SIR BPF are 3.3 GHz -3.5 GHz and 4.8 GHz -5.0 GHz with insertion loss (IL) less than 2 dB respectively. Both measured and simulated results suggest that it is a possible candidate for the application of 5G RF front-end at sub-6 GHz frequency band.     

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.     

一种紧凑型微带三频滤波器的设计

提出了一种新型微带三频滤波器,滤波器由两个弯折并相互嵌套的分支线谐振器和一个T形谐振器组成。谐振器之间相互耦合,得到三通带频率响应特性。该滤波器可通过调节微带线几何参数改变通带位置以及带宽,以满足不同应用需求。这种结构的滤波器结构紧凑,电路面积小,三个通带两边各引入一个传输零点,增强了通带间的隔离度以及阻带抑制特性。设计并制作了一款1.57/3.55/5.2GHz三通带滤波器,测试结果与仿真结果基本相符,验证了该滤波器结构的有效性。     

A compact planar ultra-wideband bandpass filter with multiple resonant and defected ground structure

A compact bandpass filter with dumbbell shape Defected Ground Structure (DGS) operating on ultra wide pass band (UWB – 3.1 to 10.6 GHz) is proposed. It is based on hybrid microstrip coplanar waveguide (dual sided metal) structure. A Multiple Resonant Structure (MRS) is constructed using coplanar waveguide (CPW) planar transmission line. The MRS makes the resonance using quarter wavelength and half wavelength open-ended CPW. The equispaced three resonances at lower (3.1 GHz), center (6.85 GHz) and higher edge (10.6 GHz) of the whole Ultra Wide Band is achieved using CPW MRS. To make the band as flat as possible, two more resonances are introduced using quarter wavelength microstrip patches on top of the commonly shared substrate, so the proposed filter becomes a five pole bandpass filter. A dumbbell shaped defected ground structure on either side of CPW MRS improves the return loss almost less than 20 dB over the whole UWB passband. The simulated results of proposed filter show good transmission response within passband and good rejection in out of the band. The simulated and measured results are very close to each other which proves the efficacy of proposed design.     

带有耦合电容的多层陶瓷带通滤波器

提出一种抽头式阶梯阻抗带通滤波器。通过在谐振器开路端引入耦合电容，增强了两个揩振器之间的耦合，从而使通带变宽，通带内衰减也变小了。因此，在不改变体积的情况下，性能比以前更好。文中采用时域有限差分方法分析这种滤波器。     

Development of tri-band RF filters using evolutionary strategy

This paper is regarding the development of a tri-band bandpass filter based on T-shape resonators for multi-standard wireless networks. The filter dimensions have been optimized by using an evolutionary strategy algorithm in order to obtain three resonance frequencies and two transmission zeros. Our algorithm is a friendly and computational intelligence approach based on biological inspirations from the parents and offsprings relations for multi-object problems. Experiments results and full-wave simulations validate the proposed strategy and demonstrate its efficiency. The filter prototype provides three bands at 0.75, 1.67 and 2.60 GHz with a maximum insertion loss of 0.99 dB.     

Miniaturized microstrip bandpass filter designed using rectangular dual spiral resonator

A miniaturized microstrip bandpass filter based on a rectangular dual spiral resonator (DSR) is proposed in this paper. The rectangular DSR bandpass filter is centered at 3.65 GHz to suit for Wireless LAN (IEEE802.11y) application. The proposed filter offers transmission zero at the high side of out-of-band response. Across the bandwidth, the measured minimum insertion loss is about 1.7 dB, while the measured return loss is better than 19 dB. Measurement results are good agreement and closed to the simulated ones. The total circuit size of the miniaturized bandpass filter is about 0.145λ_g by 0.135λ_g, where λ_g is the guided wavelength at 3.65 GHz.     

LTCC 阶梯阻抗谐振器带通滤波器的设计

结合阶梯阻抗谐振器的设计方法, 设计了一款基于低温共烧陶瓷(LTCC)工艺的阶梯阻抗谐振器带通滤波器。所设计带通滤波器除了顶部、底部接地板,中间共有三层结构, 各个相邻的谐振器之间进行宽边耦合。该带通滤波器有两个谐振腔, 中心频率约为10 GHz, 通带范围为8.9 GHz 到11.7 GHz。该带通滤波器有效地减小了体积, 总体积为3.2 mm×1.6 mm×1.7 mm。     

Improved performance step impedance lowpass filter

Performances of the conventional Butterworth step impedance lowpass filters (LPF) are significantly improved by placing transmission zero either closer to the cut-off frequency (f_c) or away from it. It is achieved by using transverse resonance width of the capacitive line sections. We report method of designing transverse resonance type LPF (TR-LPF) for 5 to 11-pole filters. At f_c = 2.5 GHz, we obtained selectivity in the range 113.3–56.66 dB/GHz and 20–60 dB rejection BW in the range 9.61–7.29 GHz. The TR-LPF can suppress the stopband signal by 60 dB up to 5f_c. Insertion loss in passband is within 0.72 dB. Improved performance of TR-LPF can be designed for f_c up to 7.5 GHz.     

Microstrip dual-band bandstop filter of defected ground structure and stepped impedance resonators

This article presents a compact microstrip dual-band bandstop filter (BSF), in which one λ_g/4 defected ground structure (DGS) pair is utilised to realise one stopband while two stepped impedance resonators (SIRs) help obtain another stopband and suppress the spurious harmonics. The design strategies and the equivalent circuits are introduced in detail. The measured results indicate 43.8% and 18.7% fractional bandwidth in the two stopbands (2.4 GHZ and 5.2 GHz) respectively, and the return loss is greater than 15 dB in the whole passband. In addition, size reduction can be conveniently achieved by adjusting the length of the SIRs and DGS.     

Compact circular-patch-based bandpass filter for ultra-wideband wireless communication systems

Ultra-wideband (UWB) is a radio technology that enables low-power-level, short-range, and wide-bandwidth communication, and it has been widely applied in personal area networks, precision geolocation, medical, surveillance, and vehicular radar systems. Since Federal Communications Commission released the unlicensed use of the UWB range (3.1–10.6 GHz), a significant attention has been paid to the development of UWB devices, particularly UWB bandpass filters. In this paper, we propose a novel UWB bandpass filter based on circular patch resonator that is grounded by via and perturbed by slits and defected ground structures. The resonator’s behaviour is analysed in detail and it is shown that its specific configuration allows a flexible control of the three lowest resonant modes, which are used to form UWB passband. To demonstrate the potential of the resonator, a UWB filter has been designed, fabricated, and measured. The filter is characterized by the insertion loss lower than 1 dB and return loss higher than 17 dB within the passband, as well as by very small group delay variation of only 0.07 ns. Also, the filter exhibits suppression higher than 19 dB up to 30 GHz, and very small overall dimensions of only 0.31λ_g × 0.31λ_g, and thus it outperforms other published UWB filters.     

MISO current mode bi-quadratic filter employing high performance inverting second generation current conveyor circuit

This paper presents static and dynamic studies of a new CMOS realization for the inverting second generation current conveyor circuit (ICCII). The proposed design offers enhanced functionalities compared to ICCII circuits previously presented in the literature. It is characterized by a rail to rail dynamic range with high accuracy, a low parasitic resistor at terminal X (1.6 Ω) and low power consumption (0.31 mW) with wide current mode (3.32 GHz) and voltage mode (3.9 GHz) bandwidths.Furthermore, a new MISO current mode bi-quadratic filter based on using ICCII circuits as active elements is proposed. This filter can realize all standard filter responses without changing the circuit topology. It is characterized by active and passive sensitivities less than unity and an adjustment independently between pole frequency and quality factor. The operating frequency limit of this filter is about 0.8 GHz with 0.674 mW power consumption.The proposed current conveyor circuits and bi-quadratic filter are tested by TSPICE using CMOS 0.18 µm TSMC technology with ±0.8 V supply voltage to verify the theoretical results.     

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.     

一种基于阶跃阻抗波导带通滤波器的设计

利用阶跃阻抗谐振器(SIR)结构设计波导带通滤波器。该方法减小体积,又可以将杂散谐振频率向高端推移,从而增加阻带宽度,使得结构的设计获得很大的自由。最后,利用电磁场仿真软件对结构尺寸进行优化仿真,并实际制作一个中心频率为780 MHz(通带差损小于0.7 dB)的SIR带通滤波器。实测结果和仿真结果吻合良好,达到预计指标参数。该滤波器具有体积小,结构简单易于加工等优点。