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1.
A new class of parallel-coupled line filters with broad stopband response is introduced. The design is based on the synthesis of bandpass prototypes with pre-defined upper stopband characteristics. The new filters have uniform- and stepped-impedance resonators, some of which are loaded by open-circuited stubs at their open-circuited ends. A seventh-order filter implementation is presented with a fundamental passband centered at 1 GHz. The measured wide-band transmission characteristic of the filter demonstrated a broad upper stopband and was in agreement with simulations. The performance of the new filter is also compared with the characteristic of a conventionally designed filter to highlight the advantages of the proposed design method. 相似文献
2.
Chi-Feng Chen Ting-Yi Huang Ruey-Beei Wu 《Microwave Theory and Techniques》2005,53(12):3788-3793
This paper proposes a bandpass filter design method for suppressing spurious responses in the stopband by choosing the constitutive resonators with the same fundamental frequency, but staggered higher order resonant frequencies. The design concept is demonstrated by a four-pole parallel-coupled Chebyshev bandpass filter and a compact four-pole cross-coupled elliptic-type bandpass filter. Each filter is composed of four different stepped-impedance resonators (SIRs) for which a general design guideline has been provided in order to have the same fundamental frequency and different spurious frequencies by proper adjusting the impedance and length ratios of the SIR. Being based on knowledge of the coupling coefficients and following the traditional design procedure, the resultant filter structures are simple and easy to synthesize. The measured results are in good agreement with the simulated predictions, showing that better than -30-dB rejection levels in the stopband up to 5.4f/sub 0/ and 8.2f/sub 0/ are achieved by the Chebyshev and quasi-elliptic filters, respectively. 相似文献
3.
Mohsen Hayati Hamed Abbasi Omid Sadeghi Fathabadi 《International Journal of Electronics》2013,100(9):1475-1485
This paper presents a novel microstrip lowpass filter with sharp roll-off and ultra-wide stopband using stepped-impedance resonator and bended transmission line structure. The filter includes stepped-impedance prototype filter and stepped-impedance compact microstrip resonator cells that are combined in one structure. The proposed filter has good specifications such as sharp roll-off, ultra-wide stopband and low insertion loss. The transition band is approximately 0.25 GHz from 1.75 to 2 GHz with corresponding attenuation levels of ?3 and ?40 dB. The attenuation level in the stopband is better than ?20 dB that is achieved from 1.94 to 23 GHz, and the insertion loss in the passband is less than 0.4 dB. The proposed filter is fabricated and measured, and the simulation and measurement results are found to be in good agreement with each other. 相似文献
4.
An edge-coupled quarter wavelength resonator and half-wavelength open stubs are used for designing a highly selective wideband bandpass filter (BPF). A homogeneous medium is considered and the even-odd mode approach is used for filter analysis. Next, a microstrip line implementation procedure is described. The filter has sharp rejection, wide stopband, low insertion loss (IL), and fabrication simplicity. A prototype BPF having 69.5% 3-dB fractional bandwidth (FBW) is fabricated. A simple stub modification extends the upper 20-dB stopband to five times that of the filter upper cutoff frequency. Passband IL is within 1.6dB 相似文献
5.
Yi-Ming Chen Sheng-Fuh Chang Chia-Chan Chang Tin-Jae Hung 《Microwave Theory and Techniques》2007,55(10):2191-2199
An enhanced stepped-impedance combline bandpass filter employs an array of stepped-impedance resonators with tapped-transformer coupling at input and output is presented in this study. This filter has enhanced performance, including symmetric insertion-loss response around the passband and wider stopband range. The structure is compact and suitable for multilayer realization because it is free of lumped capacitors and has fewer via-hole grounds. The circuit is investigated with the characteristic mode theory of coupled lines to prove the existence of multiple transmission zeros around the passband. Numerous diagrams are given for circuit design purposes. The second- and fourth-order bandpass filters at 2.45 GHz were designed, measured, and compared with the conventional combline structure to demonstrate their performance enhancement. 相似文献
6.
提出了一种用传输线在微带交叉滤波器和腔体交叉滤波器中实现交叉耦合极性改变的新方法。在微带交叉耦合滤波器中运用180°电长度的传输线实现源与非相邻谐振器的耦合,可使交叉耦合极性由容性变为感性。在腔体交叉耦合滤波器中,使用180°左右电长度的传输线,可使传输零点从阻带高端移动到阻带低端。讨论了不同电长度的传输线对交叉耦合的影响,通过调节传输线的电长度,控制传输零点的位置,提高滤波器的带外抑制。这种改变耦合极性的方法,可以用同一耦合方式获得任意位置的传输零点,给滤波器设计提供了更大的自由度。 相似文献
7.
Hong-Teuk Kim Sanghwa Jung Jae-Hyoung Park Chang-Wook Baek Yong-Kweon Kim Youngwoo Kwon 《Microwave Theory and Techniques》2001,49(9):1634-1639
In this paper, a new micromachined overlay-coplanar-waveguide (OCPW) structure has been developed and its characteristics are studied in detail as a function of the line parameters. In OCPW, the edges of the center conductors are lifted by micromachining techniques and partially overlapped with the ground plane to facilitate low-impedance lines. The elevated center conductors help to reduce the conductor loss by redistributing the current over a broad area. Comparative experiments on low-loss and lossy substrates also confirm the screening effect from the substrate losses by confining the electric field in the air between the overlapped conductor plates. Compared with the coplanar-waveguide (CPW) lines, the OCPW lines show wider impedance range (25-80 Ω) and lower loss (<0.95 dB/cm at 50 GHz). The advantages of OCPW for low-Z0 lines are utilized to realize a high-performance stepped-impedance low-pass filter at X-band. The OCPW filter shows distinct advantages over the conventional CPW filter in terms of size, loss, skirt, and stopband characteristics 相似文献
8.
Two-stage stepped-impedance resonator (SIR) filters are designed to have a wide upper stopband. Two transmission zeros are also created near the passband to form a quasi-elliptic response. For a 20-dB rejection level, with properly designed SIR geometry and tapped-line structure, the leading three spurious resonances of the SIR are suppressed by transmission zeros and respective unmatched singly loaded Q (Qsi) values. Measured results illustrate that stopbands up to 8.4 and 5.3 times the design frequency can be achieved for rejection levels of 20 and 30dB, respectively 相似文献
9.
Design of Interdigitated Capacitors and Their Application to Gallium Arsenide Monolithic Filters 总被引:1,自引:0,他引:1
《Microwave Theory and Techniques》1983,31(1):57-64
Theoretical expressions for the interelectrode capacitance and conductor losses for an array of microstrip transmission lines are presented. The effect of finite conductor thickness is included in the analysis by introducing equations for the effective width of the transmission lines. Good agreement between theory and experiment is observed up to 18 GHz. Experimental results obtained from a lumped-element GaAs monolithic bandpass filter are in excellent agreement with theory. The filter has 1.5-dB insertion loss at 11.95 GHz and greater than 22-dB loss in the stopband. The filter measures 0.58x 1.3x0.203 mm. 相似文献
10.
11.
A periodic stepped-impedance ring resonator (PSIRR) is proposed to design dual-mode bandpass filters with a miniaturized area and desirable upper stopband characteristics. Design parameters of a PSIRR include impedance ratio R of the hi-Z to low-Z sections, their lengths, and number of impedance steps 2N. The resonant characteristics of PSIRRs with various N and R values are investigated by both the transmission-line theory and electromagnetic simulation. Proper choice of the above parameters leads to an optimal reduction of circuit area and extension of upper rejection bandwidth. Two extra transmission zeros exist in the upper stopband and are tunable via changing the arm lengths of the line-to-ring coupling structure. Realized by the standard microstrip technology, the dual-mode PSIRR bandpass filter has not only the first spurious response at higher than 3.7/spl times/ the passband frequency, but also an area reduction of better than 60% against a conventional ring filter. Experimental results of several fabricated circuits validate the analysis and theoretical prediction. 相似文献
12.
Shih-Cheng Lin Tsung-Nan Kuo Yo-Shen Lin Chun Hsiung Chen 《Microwave Theory and Techniques》2006,54(8):3359-3369
Novel inline coplanar-waveguide (CPW) bandpass filters composed of quarter-wavelength stepped-impedance resonators are proposed, using loaded air-bridge enhanced capacitors and broadside-coupled microstrip-to-CPW transition structures for both wideband spurious suppression and size miniaturization. First, by suitably designing the loaded capacitor implemented by enhancing the air bridges printed over the CPW structure and the resonator parameters, the lower order spurious passbands of the proposed filter may effectively be suppressed. Next, by adopting the broadside-coupled microstrip-to-CPW transitions as the fed structures to provide required input and output coupling capacitances and high attenuation level in the upper stopband, the filter with suppressed higher order spurious responses may be achieved. In this study, two second- and fourth-order inline bandpass filters with wide rejection band are implemented and thoughtfully examined. Specifically, the proposed second-order filter has its stopband extended up to 13.3f/sub 0/, where f/sub 0/ stands for the passband center frequency, and the fourth-order filter even possesses better stopband up to 19.04f/sub 0/ with a satisfactory rejection greater than 30 dB. 相似文献
13.
Mondal P. Mandal M.K. Chakrabarty A. 《Microwave and Wireless Components Letters, IEEE》2007,17(9):643-645
In this letter, a design of a compact bandpass filter with wide upper stopband is presented for the ultra-wideband communication systems. The filter structure is composed of a modified square slot-line resonator with parallel microstrip feed lines. Improved upper stopband is obtained by exploiting the frequency dispersive coupling behavior between the feed lines and the resonator. Measurements show that the 20.9 dB upper stopband extends at least up to 20 GHz. Filter occupying area is 0.26lambdag times 0.28g, lambdag being the microstrip line guided wavelength at 6.85 GHz. 相似文献
14.
《Solid-State Circuits, IEEE Journal of》1969,4(1):38-50
The practical realization in gyrator-C form of a seventh-order Cauer-parameter low-pass filter with 40-dB stopband attenuation is described. The three floating coils of the equivalent LC filter were replaced by capacitor-loaded semi-floating gyrators. The gyrators were realized in hybrid form using thick-film resistors. The performance of the filter over a temperature range from -40/spl deg/ to +61/spl deg/C was very satisfactory, without any attempt at temperature compensation being made. This, together with the wider allowable element tolerances (compared with other active RC filter methods) shows the inherent suitability of gyrator-C filters for integration. Also in this paper some of the special problems and characteristics of gyrator-C filters are theoretically discussed, in particular the realization of gyrators with floating ports, gyrator Q-enhancement, and component tolerances in gyrator-C filters. 相似文献
15.
文中提出了一种具有宽阻带的紧凑型双频带通滤波器,它采用了折叠短路枝节负载谐振器、紧凑型微
带单元谐振器(CMRC)和阶跃阻抗谐振器结构。由于多个谐振器产生了五个可控传输零点(TZ),该滤波器实现了两个
通带之间的良好隔离度以及宽阻带特性。制作并测试了尺寸紧凑的双频带通滤波器实验样品,测试结果显示,第一通
带和第二通带的中心频率/ 插入损耗分别为0. 66 GHz/0. 8 dB 和1. 73 GHz/0. 7 dB,阻带频率高达10. 5 GHz,抑制水平
超过15 dB。 相似文献
16.
This article proposes a new dual-band tunable bandstop filter. This tunable filter is composed of two separate parts, the transmission line, and coupled stubs that each connect to three varactors. The center frequency and bandwidth in each band can be controlled individually. Moreover, the LC equivalent circuit of the proposed filter is calculated, and the results are simulated. In the proposed filter, the simulations show that the first stopband can be tuned in a frequency range from 1.2 to 1.9 GHz with 10-dB absolute bandwidth 310 ± 30 MHz, whereas the second stopband varies from 2.5 to 3.3 GHz with the 10-dB absolute bandwidth 720 ± 20 MHz. These two stopbands can also be tuned independently. Furthermore, the bandwidth of each fixed center frequency can be changed easily. The fabricated proposed filter validates the simulation results. The compact filter has an effective size of 9 × 27.5 mm2. 相似文献
17.
A synthesis procedure is described for the design of Cul-De-Sac networks realizing either bandpass or bandstop filter characteristics. The prototypes comprise a pair of one-port ladder sub-networks each connected at one of the coupled ports of a 3-dB, 90deg or 180deg hybrid coupler. Numerical examples and simulated filter layouts are presented to illustrate the design methodology 相似文献
18.
《Microwave and Wireless Components Letters, IEEE》2009,19(9):551-553
19.
Compact and wideband microstrip bandstop filter 总被引:3,自引:0,他引:3
A novel one-section bandstop filter (BSF), which possesses the characteristics of compact size, wide bandwidth, and low insertion loss is proposed and fabricated. This bandstop filter was constructed by using single quarter-wavelength resonator with one section of anti-coupled lines with short circuits at one end. The attenuation-pole characteristics of this type of bandstop filters are investigated through TEM transmission-line model. Design procedures are clearly presented. The 3-dB bandwidth of the first stopband and insertion loss of the first passband of this BSF is from 2.3 GHz to 9.5 GHz and below 0.3 dB, respectively. There is good agreement between the simulated and experimental results. 相似文献
20.
Cheng-Cheh Yu Kai Chang 《Microwave Theory and Techniques》1998,46(7):952-958
Novel compact elliptic-function narrow-band bandpass filters have been designed and fabricated. This new configuration consists of two identical microstrip open-loop resonators with coupled and crossing lines. A theoretical investigation has confirmed that this novel configuration is capable of providing elliptic-function filtering. Furthermore, the feasibility of this filter is verified experimentally. Centered at 2.039 GHz, the fabricated microstrip bandpass filter shows a measured 3-dB bandwidth of 2% and two deep notches in its stopband. In addition, the main circuit of this filter occupies only 2.5 cm×1.5 cm using a substrate with dielectric constant of 10.5, making it very attractive for applications in the mobile and personal communication systems (PCS's) 相似文献