Modeling of symmetric composite right/left-handed coplanar waveguides with applications to compact bandpass filters

This study proposes an equivalent-circuit model for the composite right/left-handed (CRLH) coplanar waveguide (CPW) comprising the series interdigital capacitor and shunt meandering short-circuited stub inductor in symmetric configuration. The new technique for extracting the equivalent-circuit elements of the CRLH CPW, which include inductances, capacitances, and resistances to represent the left-handed, right-handed, and lossy characteristics, is developed based on the effective medium concept. The applications to the compact resonators and filters are presented to emphasize the unique features of the CRLH CPW. A novel CRLH CPW resonator with a 0/spl deg/ effective electrical length at resonance is proposed, which gives a 49.1% size reduction when compared with the conventional half-wavelength resonator at 5 GHz. Based on the zeroth-order CRLH CPW resonators, an inductively coupled two-pole bandpass filter with 5.4% 3-dB bandwidth and 2.7-dB insertion loss at 5 GHz is implemented, and it is 51.4% more compact than the conventional structure. A good agreement among the results of the full-wave simulation, equivalent-circuit model, published data, and measurement demonstrates the effectiveness of the proposed modeling technique. To suppress the higher order harmonic spurious passbands, the electromagnetic-bandgap CPW structures are incorporated into the proposed CRLH CPW filter.     

High Aspect-Ratio Coplanar Waveguide Wideband Bandpass Filter With Compact Unit Cells

This paper introduces a micromachined thick single-metal-layer high aspect-ratio coplanar waveguide (CPW) wideband bandpass filter with compact unit cells based on the electromagnetic bandgap (EBG) concept. The filter is miniaturized as a result of using the EBG concept in design, and also by realizing high aspect-ratio structures with polymer-based deep X-ray lithography fabrication. Cascaded unit cells in the EBG model consist of capacitive and inductive parallel periodically loaded transmission lines, which determine the filter bandwidth. Compact unit cells are realized by using high aspect-ratio CPW stepped-impedance resonators. The main advantage of this approach is that the high aspect-ratio CPW structures make short unit cells practically realizable, resulting in a compact filter structure. A bandpass filter with 47% bandwidth is designed and fabricated using deep X-ray lithography, and the performance and physical size is compared to a conventional quarter-wavelength-based admittance inverter filter.      

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.     

Bandpass Filter with Wide Stopband Using Composite Right/Left Handed Transmission Line

Abstract This paper presents a wide-stopband bandpass filter (BPF) based on mixed coupling of the composite right/left handed transmission line (CRLH-TL). First the CRLH-TL resonator is introduced and analyzed. Then mixed coupling (Both electric coupling path and magnetic coupling path exist) of the novel resonator is explained. Based on the structural features of the CRLH-TL resonators, this coupling path can generate an additional transmission zero near passband without increasing the overall size of the filter. Then, good selectivity of the proposed BPF can be obtained. Meanwhile, in order to get a wide stopband, two open stubs are employed to suppress harmonic response of the CRLH-TL resonator. The filter is developed and analyzed based on microwave network theory and equivalent circuit method. The proposed BPF has been designed, fabricated, and measured. The measured results agree with the predicted ones closely.     

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.     

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     

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.     

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     

HTS coplanar meander-line resonator filters with a suppressed slot-line mode

The design and experimental results of a four-pole coplanar waveguide (CPW) quasi-elliptic filter using high-temperature superconductor (HTS) films are presented. Quarter-wavelength meander-line resonators are used in the filter topology. Although the resonators are aligned in two lines, no bond-wire bridges are required to balance the ground planes in the design and measurement. The slot-line mode of the filter was shifted to be higher than its third harmonic. The filter is highly miniaturized and the performance is significantly improved by the use of superconductors. The main circuit of the filter only has an area of about 6.6 mm /spl times/ 2.4 mm on a magnesium oxide substrate, coated with 600-nm-thick YBCO HTS thin film on single side of the substrate. The 3-dB bandwidth is about 1.6% centered at 2.95 GHz. The performance measured at 30 K, without any tuning, gives an insertion loss of better than 0.4 dB and a return loss of about 12 dB in the passband. The first spurious mode is about triple the center frequency.     

A Fully Embedded LTCC Multilayer BPF for 3-D Integration of 40-GHz Radio

This paper demonstrates a low loss fully embedded multilayer bandpass filter (BPF) using low-temperature cofired ceramic (LTCC) technology for 3-D integration of 40-GHz multimedia wireless system (MWS) radio. The LTCC filter implemented in a stripline configuration occupies an area of only 5.5 times 2.3 times 0.6 mm including shielding structure and coplanar waveguide (CPW) transitions. The measured insertion loss was as small as 1.9 dB at a center frequency of 41.8 GHz, and the return loss was 12.2 dB including the loss associated with two CPW-to-stripline transitions. This six-layer BPF showed 3-dB bandwidth of 10.5% from 39.6 to 44.0 GHz at a center frequency of 41.8 GHz and suppressed the local oscillator (LO) signal to 20.2 dB at a local oscillator frequency of 38.8 GHz, making it suitable for the 40 GHz MWS applications.     

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.      

基于交指结构和双模谐振器的双频微带滤波器*

提出了一种应用于宽带系统和窄带系统的双频微带滤波器,其宽带通带和窄带通带分别通过三阶交 指型滤波结构和双模微带谐振器来控制。两部分的相互加载效应可进一步增强源-负载耦合,提高通带的选择性。 在50赘馈线上加载两个不同尺寸的反向四分之一波长谐振器(QWR)耦合短路枝节,可以在通带之间及上下边缘处 产生多个传输零点,提高了通带选择性和隔离度。最终,本文设计了一个工作于3.2GHz(宽带)和5.8GHz(WLAN) 的双频滤波器用以验证上述设计方法,测试和仿真结果吻合良好。     

单槽双频微波带通滤波器设计与实现

在方形贴片上采用单槽线代替相互正交双槽线的方法设计出一款结构简单、紧凑的双频段带通滤波器。详细讨论了滤波器结构参数对滤波器性能的影响,并以2.45/5.2GHz双通带滤波器的设计为例,通过仿真优化得到了各结构参数,制作了相应的样品。测试结果表明：该滤波器在2.45GHz通带内回波损耗为20dB,通带内最小插损为0.9dB,相对带宽为10%;5.2GHz通带内回波损耗33.6dB,通带内最小插损为0.37dB,相对带宽为13.4%,其总体尺寸比文献中正交双槽线结构的滤波器缩小48%。     

A novel compact dual-wideband BPF with multiple transmission zeros and super wide upper stopband

In this article, a novel miniaturised dual-wideband bandpass filter (DWB-BPF) based on two different resonators including a quasi-spiral loaded multiple-mode resonator (QSL-MMR) and L-shaped transmission line (LS-TL) is presented. At the first step, in order to design a single wideband BPF filter with controllable transmission zeros near the centre frequency, the open circuit impedance parameter of quasi-spiral loaded resonator Z₂₁ is determined in terms of ABCD matrix. Then an equivalent circuit model of the proposed structure is derived and the impedance characteristic and electrical length of LS-TLs to achieve a DWB-BPF with excellent selectivity are calculated through even- and odd-mode analysis. The proposed filter possesses both compact and simple structure as well as two wide passbands with fractional bandwidth (FBW) of 70% and 22.8% for its first and second passbands, respectively. The proposed technique creates two transmission zeros at the lower and upper stopbands of each passband resulting in a very sharp roll-off accompanied by a wide stopband. Notably, the circuit size is reduced and the bandwidth is enhanced in comparison with its conventional counterparts. The theoretical performance of the filter is verified by the experimental one where a good agreement is reported between them.     

Compact Millimeter-wave filters using distributed capacitively loaded CPW resonators

In this paper, a method for reducing the size of coplanar-waveguide (CPW) resonators, used in the design of compact bandpass filters, is presented. This is accomplished by incorporating a distributed array of capacitive loads along a resonant CPW line. Design of a miniaturized bandpass filter using capacitively loaded CPW resonators, which are inductively coupled, is presented. Inductively coupled bandpass filters with the proposed capacitively loaded CPW line resonators are designed and a size reduction of 25%, compared with filters using a standard CPW line resonator, is demonstrated. It is shown that, through this size reduction, the insertion loss is minimally increased (<0.4 dB). A hybrid algorithm, combining the method of moments (MOM) and circuit simulation is used to facilitate design process. Few filters using this technique are designed, fabricated, and measured at W-band. An excellent agreement between the simulation and measurement responses of these filters is presented.     

A Fully Embedded 60-GHz Novel BPF for LTCC System-in-Package Applications

In this paper, a novel LTCC stripline (SL) 60-GHz band-pass filter (BPF) composed of transitions to coplanar waveguide (CPW) pads for monolithic microwave integrated circuit integration is presented. For low-loss interconnection with active devices, a CPW-to-SL vertical via transition integrating air cavities and a CPW-to-CPW planar transition using internal ground planes are proposed and implemented. The fabricated transition shows an insertion loss of 1.6 dB and a reflection loss below -20 dB at the passband of the filter. The implemented SL BPF using dual-mode patch resonators shows a center frequency of 60.4 GHz, 3.5 % bandwidth, and reflection losses below -15 dB at the passband. Excluding the insertion loss of the transitions, the filter insertion loss reveals 4.0 dB     

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.     

An implementation of harmonic-suppression microstrip filters with periodic grooves

In this paper, a new parallel-coupled-line microstrip band pass filter (BPF) improving the harmonic suppression performance of the second harmonic signal (2f/sub o/, twice the passband frequency) is described. It is found that the desired passband performance is improved and the harmonic passband signal is diminished by enforcing the consecutive patterns in coupled-line and increasing the number of grooves to the optimum values. The recalculation of design parameters such as space-gap between lines, line widths and lengths is not required due to the simple modification of the conventional filter by inserting periodic patterns. To evaluate the validity of this novel technique, order-3 Butterworth BPF centered at 2.5 GHz with a 10% fractional bandwidth (FBW) and order-5 Chebyshev BPF centered at 10 GHz with a 15% FBW were used. When five and three square grooves are used, over 30-dB suppression at second harmonic signal is achieved in simulation and experiment. Finally, the comparison between the characteristics of filters with square and semicircular periodic grooves has been carried out by using the simulated results.     

Novel Phase Noise Reduction Method for CPW‐Based Microwave Oscillator Circuit Utilizing a Compact Planar Helical Resonator

This letter describes a compact printed helical resonator and its application to a microwave oscillator circuit implemented in coplanar waveguide (CPW) technology. The high quality (Q)‐factor and spurious‐free characteristic of the resonator contribute to the phase noise reduction and the harmonic suppression of the resulting oscillator circuit, respectively. The designed resonator showed a loaded Q‐factor of 180 in a chip area of only 40% of the corresponding miniaturized hairpin resonator without any spurious resonances. The fully planar oscillator incorporated with this resonator showed an additional phase noise reduction of 10.5 dB at a 1 MHz offset and a second harmonic suppression enhancement of 6 dB when compared to those of a conventional CPW oscillator without the planar helical resonator structure.