Compact Wideband Bandpass Filters With Wide Upper Stopband

In this letter, a T-shaped microstrip feeding arrangement is proposed to design wideband bandpass filter (BPF) using shorted slot-line resonators. This feed line produces frequency selective external coupling which is utilized to suppress unwanted harmonics. Up to sixth order harmonics are suppressed. Other advantages are low passband group delay variation, ease of fabrication, low insertion loss (IL), and compact size. A fabricated BPF of fractional bandwidth 56.3% at midband frequency 2.3 GHz has a maximum IL of 1.2 dB in its passband and 30-dB upper stopband extends over 11.53 GHz     

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     

园杆梳状线微波带通滤波器的研制

给出了一种中心频率为1.675GHz园杆梳状线微波带通滤波器的设计过程.设计方法采用等效电路原理,并用HFSS软件仿真优化.所设计滤波器采用园杆梳状线结构,其结构紧凑,体积小,便于加工.文中将实测曲线和仿真曲线进行了比较,二者吻合很好.     

Design of a Wide Stopband Microstrip Bandpass Filter With Asymmetric Resonators

In this letter, a novel microstrip bandpass filter (BPF) with asymmetric resonators is presented. With the asymmetric structure and capacitively loaded coupling, a wide bandwidth with sufficient rejection level can be achieved easily. A full-wave electromagnetic simulator IE3D is used, and the prototype of the BPF is fabricated and measured. Comparisons of simulated results and experimental data are shown; moreover, good match validates the proposed filter.     

Design of a Wide Stopband Microstrip Bandpass Filter With Interdigital Resonators

In this letter, a novel microstrip bandpass filter (BPF) with interdigital resonators is presented. With the interdigital resonators and shorted asymmetrical coupled-lines, a wide bandwidth with sufficient rejection level can be achieved easily. A full-wave electromagnetic simulator IE3D is used, and the prototype of the BPF is fabricated and measured. Comparisons of simulated results and experimental data are shown; moreover, good match validates the proposed filter.      

Coplanar Waveguide Bandpass Filters With Compact Size and Wide Spurious-Free Stopband Using Electromagnetic Bandgap Resonators

This work presents a novel coplanar waveguide (CPW) bandpass filter (BPF) that uses electromagnetic bandgap (EBG) resonators to reduce the size and suppress the harmonic responses. The propagation characteristic of the EBG structure is investigated by its associated equivalent circuit model. Compared with the conventional half-wavelength resonator at 5GHz, the EBG resonator is 60.5 % more compact. Based on the EBG CPW resonators, the inductively-coupled two-pole BPF with 3.8% 3-dB bandwidth and 2-dB insertion loss at 5GHz is implemented. This structure generates a 59.6% reduction in size and suppresses a second harmonic passband when compared with a conventional filter. To eliminate the third harmonic response, the proposed EBG CPW BPF further incorporates two EBG structures into its input and output ports and has the merit of a small circuit area     

A Wideband Bandpass Filter With Wide Upper Stopband Using Stepped-Impedance Cascadable 180 ° Hybrid Rings

This letter proposes a wideband bandpass filter by cascading two 3-dB stepped-impedance cascadable 180deg hybrid rings with a pair of stepped-impedance lines. Thanks to the stepped-impedance lines, a broad upper stopband is achieved. The stepped-impedance vertically installed planar (VIP) coupler is used to implement the ideal 180deg phase inverter and crossovers. The experimental results show that this 2-GHz center frequency, fourth order filter has a 10-dB return loss bandwidth of 92.5% and upper stopband rejection levels of better than -20 dB up to 6.8 GHz. This proposed filter achieves wide passband and broad stopband performance simultaneously.     

一种新型宽阻带管状带通滤波器的设计

为改进原管状带通阻带特性,设计了一种新型结构.基于阻抗匹配,可在端头引入任意多“r型”网络.同时其衰减极点能有效抑制“谐振峰”状寄生,阻带拓宽多达1倍频程(现为1.27fo～17fo).改进后,滤波器具有低插损(小于等于0.77 dB)、轻量化(小于等于64 g)、高寄生抑制(大于等于75 dB)等特点.目前,该滤波器...     

Compact Electronically Switchable Parallel-Coupled Microstrip Bandpass Filter With Wide Stopband

In this letter, a compact electronically switchable parallel-coupled microstrip bandpass filter (BPF) based on quarter- wavelength resonators and p-i-n diode switch is proposed. The proposed filter occupies only half the circuit size of the conventional parallel-coupled filter. In addition, the type and length of each coupled-line section is suitably chosen such that the inherent transmission zeros associated with the coupled-lines can be used to reject the spurious passbands effectively. By adding only one p-i-n diode along with a simple bias control circuitry, the proposed filter becomes electronically switchable with no current consumption when the filter is turned off. Specifically, a switchable fourth-order microstrip BPF with a center frequency f₀ of 2 GHz, passband insertion loss less than 3 dB, and wide stopband up to 7.7 f₀ in the ON state is demonstrated. The isolation of the filter is better than 30 dB from dc up to 7.7 f₀ in the OFF state.     

多传输零点LTCC梳状线带通滤波器的设计与实现

设计了一种改进型的梳状线LTCC滤波器.在一般抽头式梳状线滤波器设计的基础上,结合电路仿真以及三维电磁场仿真,辅之以DOE(design of experiment)的设计方法,设计出一种高抑制、低插损多传输零点的滤波器.滤波器的实际实现采用在当今射频通信器件设计中流行的LTCC技术.该滤波器中心频率为2.45GHz,带宽150MHz,可以广泛运用于无绳电话、蓝牙模块,以及WLAN的射频电路中.     

Design of the Compact Parallel Coupled Wideband Bandpass Filter With Very High Selectivity and Wide Stopband

In this letter, a compact and high performance parallel coupled line wideband bandpass filter (PCL-WBF) with open stubs is designed and implemented on the commercial substrate, RT/Duroid 5880. The PCL-WBF is composed of a one-stage coupled line and two open stubs connected near the input/output ports. The design procedure and limit are discussed in detail. The designed filter was fabricated and measured, showing good characteristics of wide stopband and very high passband selectivity. Measured results also have a good agreement with the simulated results.     

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.      

一种小型化宽阻带窄带通滤波器研究

为实现滤波器设计小型化,降低带通滤波器的高次谐波干扰,本文结合传统的1/4波长谐振器结构,采用在谐振器微带线上添加开路线的方法,降低高次谐振频点处的插入损耗,消减谐波影响。相比半波谐振器,1/4波长谐振器能有效地减小滤波器尺寸,此外开路线的添加除具有消减高次谐波作用,同时还能降低基频谐振点,促进设计小型化。通过仿真软件对该方案的验证及网络分析仪的实物测试表明,此方案具有良好效果,能广泛应用于窄带通滤波器小型化及谐波抑制。     

Synthesis of Dual-Band Bandpass Filters with Asymmetric Stepped-Impedance CBACPW Resonators

A novel Dual-band bandpass filter （DBBPF） with an asymmetric topology and stepped- impedance Conductor-backed asymmetric coplanar waveg- uide （CBACPW） resonators is proposed in this paper. Compared with the existing DBBPFs with a same low-pass prototype, two additional transmission zeros are emerged by using the asymmetric topology. To facilitate the filter synthesis, design formulas of the filter are derived, and an ANN-based synthesis model of CBACPWs is developed. To validate the filter synthesis method, a DBBPF oper- ating at GSM and GPS bands is designed, simulated and measured. A good agreement between simulation and mea- surement is obtained.     

电调梳状带通滤波器的设计

本文设计了一种能够在特高频（UHF）工作的可电调梳状微带线带通滤波器,可通过调节加在变容二极管两 端的电压值实现滤波器工作频率的改变,可调工作频段为500MHz-1000MHz,电压调节范围为1-13V。具有带宽小、 阻带抑制高、结构小型化、易程控迅速精确切换频率以及加工一致性较好等特点。文中还就变容二极管选取、建模以 及一些敏感的参数等做了讨论。     

Miniaturized Dual-Mode Circular Patch Bandpass Filters With Wide Harmonic Separation

Two slots oriented orthogonal to each other are cut on a circular patch resonator. The slots bring down the fundamental resonance frequency of the patch. The second higher order mode, however, remains unaffected. This effectively miniaturizes the patch by 57.8% at the same time increases the harmonic separation by 2.51 times. By adding two more slots parallel to and on both the sides of each arm of the crossed slot, fundamental frequency can be further brought down resulting in a filter which is 87.4% smaller compared to a circular patch. The second passband appears at a frequency which is 4.66 times that of the first passband center frequency.      

Compact Wideband Bandpass Filters Using Stepped-Impedance Resonators and Interdigital Coupling Structures

This letter proposes a microstrip $lambda/4$ interdigital stepped-impedance resonator whose impedance ratio can be very low and coupling strength between adjacent resonators can be very large. On the basis of the proposed structure, one four-pole Chebyshev and one four-pole generalized Chebyshev filter with 0.05 dB equal-ripple bandwidths of 48% and 46%, respectively, are designed and fabricated. Both implemented filters have a compact size, a wide passband, a wide upper stopband, and a high spurious passband at near 5.1 times the center frequency. Good agreement between measurements and simulations is observed.      

Wide-Stopband Microstrip Bandpass Filters Using Quarter-Wavelength Stepped-Impedance Resonators and Bandstop Embedded Resonators

Novel compact microstrip bandpass filters (BPFs) with extended stopband are proposed using both quarter-wavelength (lambda/4) stepped-impedance resonators and bandstop embedded resonators. First, by properly designing the impedance and length ratios of the stepped-impedance resonators, the developed filter may be made compact and its spurious harmonics may be pushed to the higher frequency region. Next, by suitably designing the bandstop structure so as to suppress the lower spurious harmonics of stepped-impedance resonators and then embedding the bandstop structure into the lambda/4 resonators, one may realize the BPFs with wideband spurious suppression. In particular, by connecting the bandstop embedded resonators to the input/output ports, a compact fourth-order BPF of dimension 0.089 lambdag times 0.27 lambdag is implemented and its stopband is extended up to 8.25 f ₀ with an adequate rejection of greater than 32.49 dB, where f ₀ is the passband center frequency and lambdag is the microstrip guided wavelength at f ₀.     

Synthesis of Combline and Capacitively Loaded Interdigital Bandpass Filters of Arbitrary Bandwidth

Synthesis procedures are presented for commensurate linelength combline and capacitively loaded interdigital filters. A simple modification for using lumped capacitors is given and is found to yield excellent results for any practical bandwidth. The synthesis procedures for both filter types follow directly from the classical bandpass filter design approach using a transformed frequency variable. Two design examples are given to illustrate the design procedures and experimental results are presented for a 40 percent bandwidth combline filter. The problems of network sensitivity, use of network equivalents, and extension to other filter types are also discussed.     

一种基于互异结构的宽阻带带通滤波器研究

针对带通滤波器的高次谐波干扰,结合目前常用的在输入输出微带馈线上添加开路线构成带阻的方法,采用两个互异的中间添加开路线的阶跃阻抗开环谐振器来实现高次谐振频点的相互分离,达到抑制高次谐波实现宽阻带的目的。通过仿真软件对这一方案的验证及网络分析仪的实物测试证明,该方案具有良好的效果,能广泛应用于带通滤波器的谐波抑制。