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.     

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     

A Compact Ultra-Wideband Bandpass Filter Based on Split-Mode Resonator

A compact ultra-wideband (UWB) bandpass filter is proposed based on the coplanar-waveguide (CPW) split-mode resonator. By suitably introducing a short-circuited stub to implement the shunt inductance between two quarter wavelength CPW stepped-impedance resonators, a strong magnetic coupling may be realized so that a CPW split-mode resonator may be constructed. Moreover, by properly designing the dual-metal-plane structure, one may accomplish a microstrip-to-CPW feeding mechanism to provide strong enough capacitive coupling for bandwidth enhancement and also introduce an extra electric coupling between input and output ports so that two transmission zeros may be created for selectivity improvement. The implemented UWB filter shows a fractional bandwidth of 116% and two transmission zeros at 1.705 and 11.39 GHz. Good agreement between simulated and measured responses is observed.     

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.     

Compact UWB bandpass filter with improved upper-stopband performance

a compact microstrip-line ultra-wideband (UWB) bandpass filter (BPF) using aperture-backed interdigital coupled lines and a stub-loaded folded stepped-impedance resonator (SLFSIR) is presented. in the design, the first four resonant frequencies of this SLFSIR are properly adjusted to be placed evenly within the UWB while the fifth resonant frequency is raised above 16.0 GHz to improve upper-stopband performance. furthermore, the aperture-backed interdigital coupled lines can create a transmission zero to cancel the fifth resonant mode of the SLFSIR to make a wider upper-stopband as well as raising the coupling degree to relax the tight line spacing. after optimisation of this filter, good UWB bandpass behaviour is theoretically realised and experimentally confirmed.     

Ultra Wideband Bandpass Filter Using Embedded Stepped Impedance Resonators on Multilayer Liquid Crystal Polymer Substrate

This letter proposes an ultra wideband (UWB) bandpass filter (BPF) based on embedded stepped impedance resonators (SIRs). In this study, broad side coupled patches and high impedance microstrip lines are adopted as quasi-lumped elements for realizing the coupling between adjacent SIRs, which are used to suppress stopband harmonic response. An eight-pole UWB BPF is developed from lump-element bandpass prototype and verified by full-wave simulation. The proposed filter is fabricated using multilayer liquid crystal polymer (LCP) process and measured using vector network analyzer. Good agreement between simulated and measured response is observed. The measurement results show that the fabricated filter has a low insertion loss of 0.18 dB at center frequency 6.05 GHz, an ultra wide fractional bandwidth of 127.3% and excellent stopband rejection level higher than 32.01 dB from 10.9 to 18.0 GHz.      

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     

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.     

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.     

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     

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     

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     

Ultra-Wideband (UWB) Bandpass Filters With Hybrid Microstrip/Slotline Structures

A novel ultra-wideband (UWB) bandpass filter is presented using back-to-back microstrip-slotline transition and triple-mode slotline resonator. A uniform slotline resonator is constructed with a length of one full wavelength at the central frequency. Two microstrip feed lines are then placed above the slotline resonator to make up a back-to-back microstrip-slotline transition, where two intersection points are equally located at one quarter-wavelength away from two short-ends. By properly stretching the microstrip line lengths, an ultra-wide passband is constituted with the lower/upper cut-off edges dominated by the first/third resonant modes.By forming a W-shaped slotline resonator, introducing a cross coupling and cascading two lowpass filters, two UWB bandpass filters with improved out-of-band performances are designed, fabricated and measured. Measured results achieve a 2.56-to-10.90 GHz or 124% passband with return loss >12.04 dB, group delay variation <0.58 ns, sharpened rejection skirts and extended upper-stopband.     

基于新型谐振器的超宽带带通滤波器

采用两个新型四阶阶梯阻抗谐振器设计出一种新型超宽带带通滤波器,四个1/4波长的耦合线被平行放置于输入输出端,起到增加耦合强度的作用,三个谐振频率被调整在超宽带带宽(3.1 GHz～10.6 GHz)内。通过优化后,该滤波器在通带内具有五个传输极点,频带宽度在3.6 GHz～10.5 GHz,通带内回波损耗优于15 dB,最小插入损耗为0.6 dB,满足超宽带的传输要求。仿真结果显示,文中设计的滤波器具有小型化、低插入损耗和较好的带外特性等优点。     

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.     

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.      

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。     

Planar microstrip UWB bandpass filter using U-shaped slot coupling structure

A compact planar microstrip UWB bandpass filter is proposed. It is realised by cascading a lowpass filter and a highpass filter. A transmission line with U-shaped slots coupled with two DGS units on the back of the circuit board has the characteristic of highpass, while a periodic uniform DGS array has the characteristic of lowpass. Combining these two structures, a new UWB bandpass filter (BPF) is fabricated and measured. Measured results show that the proposed BPF has wide bandwidth from 3.0 to 10.9 GHz, all the measured return loss less than 13 dB in the passband. The BPF achieves a wide stopband with 18 dB attenuation up to 18.0 GHz     

A 3.3 mW K-Band 0.18-μ m 1P6M CMOS Active Bandpass Filter Using Complementary Current-Reuse Pair

This letter presents a low-power active bandpass filter (BPF) at K-band fabricated by the standard 0.18 mum 1P6M CMOS technology. The proposed filter is evolved from the conventional half-wavelength resonator filter, using the complementary-conducting-strip transmission line (CCS TL) as the half-wavelength resonator. Furthermore, the complementary MOS cross-couple pair is proposed as a form of current-reuse scheme for achieving low-power consumption and high Q-factor simultaneously. The simulated results indicate that the Q-factor of the proposed half-wavelength resonator can be boosted from 9 to 513 at 25.65 GHz compared with the resonator enhanced by the nMOS cross-couple pair to Q-factor of merely 43 under the same power consumption. The proposed active BPF of order two occupies the chip area of 360 mum times 360 mum without contact pads. The measured results show that the center frequency of the active BPF is 22.70 GHz and a bandwidth of 1.68 GHz (7.39 %). The measured P_{1 dB} and noise figure at 22.70 GHz are -7.65 dBm and 14.05 dB, respectively. There is a 56.84 dB suppression between the fundamental tone and the second harmonic when the input power is -11.26 dBm. While showing 0 dB loss and some residual gain, the active BPF consumes 2.0 mA at 1.65 V supply voltage with maximum of 0.15 dB insertion loss and 9.96 dB return loss at pass band.     

Asymmetric dual-line coupling strip for multiple notched bands: Theory and implementation

An asymmetric dual-line coupling strip (ADLCS) can provide main two paths for the signals, which make it possible to generate multiple transmission zeroes. The detailed analysis of the ADLCS is proposed in this paper. Based on the microwave network theory, the equivalent circuit of the ADLCS is also developed. Moreover, the structural parameters of ADLCS are studied by calculations and simulations. The center frequencies and bandwidths of the notch bands can be controlled by tuning the structural parameters. Obviously, The ADLCS can be used in the ultra-wideband (UWB) bandpass filter (BPF) to generate multiple notch bands within the passband. To demonstrate the performance of the ADLCS with UWB filter, the structure is applied to the input and output (I/O) of the single-stage UWB Y-shaped BPFs. The proposed UWB Y-shaped BPF has been designed, fabricated, and measured. The measured results agree with the predicted ones closely. The two notch bands of the fabricated UWB Y-shaped BPF centered at 4.5 and 8.1 GHz have 10-dB rejection fractional bandwidths of about 5.6% and 5%, respectively.