Bandpass Filter For Applications Research Articles

Single Active Element Based Cascadable Band-Pass Filters for Low-Q Applications

The paper presents new single active element based second order band pass filters. The new circuits use single dual-X current conveyor with buffered output and five passive components. The proposed circuits enjoy the features of high input impedance and low output impedance, which are desirable features for voltage-mode circuits. Circuit operation at high frequencies are verified along with non-ideality and parasitic study. The Monte Carlo analysis is also done which justify good sensitivity performances of the proposed circuits. Routh–Hurwitz's stability test is performed to verify the stability of the proposed circuits. For showing the integration aspect, resistorless band-pass filters are also realized. The proposed low-Q filters are useful for cascading. The feature of cascadability is further utilized by showing an application of fourth-order band-pass filter. The performances of the proposed circuits are depicted through Personal Simulation Program with Integrated Circuit Emphasis (PSPICE) simulations, which show good agreement to theoretical applications. The new circuits are expected to enhance the already existing knowledge on the subject.

A Configuration for Realizing Voltage Controlled Floating Inductance and Its Application

A configuration using current feedback amplifiers AD844 and multiplier AD534 has been presented, which is capable of realizing Voltage Controlled Floating Inductance (proportional and in-verse proportional). The application of band pass filter in Figure 4(a), notch filter in Figure 5(a) and Hartley oscillator in Figure 6(a) and simulation result in Figures 4(b)-(d), Figures 5(b)-(d), Figures 6(b)-(d) shows the workability of proposed configuration.

New π –T generalised metamaterial negative refractive index transmission line for a compact coplanar waveguide triple band pass filter applications

This study presents, for the first time, a novel π − T generalised negative refractive index (NRI) transmission line (TL) configuration. It is innovated for increasing the possible passbands in designing microwave components. It is proved that the proposed transmission line can introduce up to seven passbands for completely unbalanced transmission line condition. The detailed mathematical analysis of that configuration based on the periodic network analysis and equivalent circuit model is introduced. As an application for the novel π − T generalised NRI TL configuration, a new compact triple band coplanar waveguide (CPW) metamaterial filter is introduced. The proposed triple bands CPW filter design steps are introduced and its performance is validated using equivalent circuit model simulation, electromagnetic full wave simulation and experimental measurements. Good agreements between the circuit modelling, electromagnetic full wave simulation and practical measurement results are achieved. All the results confirm that the proposed filter has triple passbands from 900 to 960 MHz, 1.4 to 1.48 GHz and 2.4 to 2.45 GHz. Moreover the filter size is compact whose length is only 12.1% λg at first passbands, 18.2 λg % at second passbands and 31.7 λg % at third passbands.

Electric Coupling Structure of Substrate Integrated Waveguide (SIW) for the Application of 140-GHz Bandpass Filter on LTCC

Millimeter-wave (mmW) bandpass filters (BPFs) using substrate integrated waveguide (SIW) are proposed in this paper. The propagation constants of two different types of electromagnetic bandgap (EBG) units are discussed and compared for their passbands and stopbands performance. In among, the slotted-SIW unit shows a very good lower and upper-stopband performance. The mmW BPF with three cascaded uniform slotted-SIW-based EBG units is constructed and designed at 40-GHz. This EBG filter exhibits good out-of-band performance. To further improve the in-band performance, a third-order mmW BPF with nonuniformly cascaded slotted-SIW unit is designed at 140 GHz. The filter is investigated with the theory of electric coupling mechanism. The extracted coupling coefficient (K) and quality factor (Q) are used to determine the filter circuit dimensions. To prove the validity, the two proposed structures are fabricated in a single-circuit layer using low temperature co-fired ceramic technology and measured at 40 and 140 GHz, respectively. The measured results are in good agreement with the simulated results in such high frequency. The measured insertion losses at 40 GHz and 140 GHz are 0.72 and 1.913 dB, respectively.

Lossless grounded inductance simulator employing single VDBA and its experimental band-pass filter application

Actively simulated grounded inductors have been used in several applications ranging from filter to oscillator design as well as cancelation of parasitic inductances. In this paper, new lossless grounded inductance simulator employing only one voltage differencing buffer amplifier (VDBA) and two passive components is proposed. The aim of this paper is to present new inductance simulator using the minimum number of active and passive components. The proposed inductance simulator can be tuned electronically by changing the transconductance of the VDBA. Finally, using the proposed inductance simulator a band-pass filter is constructed. The performance of the filter is simulated by using PSPICE and simulation results are verified experimentally.

Design of electron wave filters in monolayer graphene with velocity modulations

We compare the transport properties of electrons in monolayer graphene by modulating the Fermi velocity inside the barrier. A critical transmission angle is found only when the Fermi velocity in the barriers is larger than the one outside the barriers. It is shown that the transmission exhibits periodicity with the incident angle below the critical transmission angle, and attenuates exponentially in the opposite situation. For both situations, peak splitting occurs in the transmission as the number of the velocity barriers increases, and the characteristics of the transmission suggest an interesting application of an excellent band-pass filter. The dependence of the conductance on the Fermi energy through an identical velocity-modulation structure differs wildly with different Fermi velocities of the barrier. The counterpart of the peak splitting is the sharp oscillations in the conductance profile. Furthermore, some oscillations for the multiple barriers are so sharp that the structure may be used as an excellent sensor.

HIGH QUALITY FACTOR L-BAND ACTIVE INDUCTOR-BASED BAND-PASS FILTERS

In this letter, a tunable high-Q active inductor with high dynamic range is presented. The equivalent inductance and resistance values can be tunable in a wide frequency range by changing the compensating network components values; outside the operating frequency band, the equivalent resistance increases, improving signal rejection for band-pass filter applications. A second-order active band-pass filter with a central frequency of 2100 MHz using the high-Q active inductance has been fabricated and tested.

A novel compact configuration for dual-mode microstrip resonators and dual-band bandpass filter applications

In this article, a novel compact dual-mode resonator formed by a square loop having folded arms and mitered bends is proposed.Degenerate modes can be excited by shifting the gaps between the folds. Thus, the center frequency can be arranged at a fixed value because the total electrical length of the proposed configuration is not changed. A novel compact dual-mode dual-band bandpass filter is also designed by locating the one resonator within the other. Additionally, to suppress the harmonic of the first passband, open-circuited stubs are connected to the end of the feedlines. Two dual-mode dual-band bandpass filters with the elliptical and linear phase filtering characteristics for both passbands have been designed, fabricated, and tested. Calculated, simulated, and measured results are in a good agreement. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:775–779, 2013; View this article online at wileyonlinelibrary.com. DOI: 10.1002/mop.27444

A COMPACT DUAL-MODE RESONATOR WITH SQUARE LOOPS AND ITS BANDPASS FILTER APPLICATIONS

In order to realize bandpass fllter with Chebyshev and elliptic function responses using a single resonator only, a dual-mode square resonant structure is proposed. Four small square loops are added into a large loop. One of small loops is deflned a perturbation element, other small ones are references. By changing the thickness of the perturbation element with respect to that of a reference element, the resonator can produce a capacitive or inductive coupling between two degenerate modes. The capacitive coupling can acquire an elliptic function characteristic since it can create the transmission zeros on both the lower and upper sides of the pass band, while the inductive coupling cancels them which exhibit a Chebyshev characteristic. Therefore, both Chebyshev and elliptic function responses can be obtained for the fllter. The proposed device is with a wider stopband and more compact in size. Experiment results have been verifled this design.

Application of Windowed-sinc Band-pass Filter to Accurate and Fast Calculation of Impedance for Digital Distance Relaying

Extraction of fundamental components of both voltage and current is essential and is a challenge in digital distance protection. This paper introduces an effective filtering technique to fulfil this purpose. The technique proposed here is to use a windowed-sinc band-pass filter, which presents an outstanding immunity to both DC and harmonic components' influence when used to extract fundamental components of voltage and current. Then, the computed impedance is an accurate indication of the fault point along a transmission line and experiences the least amount of fluctuation. Compared to existing algorithms, it has a faster determination of the fault impedance of the line under protection and it takes slightly more than half a cycle of 50Hz system to reach the accurate impedance value. An experiment was also conducted to verify the validity of the designed filter to extract 50Hz fundamental component. 

Bandpass filter based on low frequency spoof surface plasmon polaritons

Based on the mechanism of spoof surface plasmon polaritions (spoof SPPs), a kind of microwave bandpass filter is presented in both theory and experiment, which is realised by a periodic subwavelength metallic Domino array. The transmission bandwidth of spoof SPPs is controllable by designing the geometric parameters of the periodic structure. Simulation and experimental results of the spoof SPPs agree well with each other and verify the feasibility in bandpass filter applications.

Design of dual-band bandpass filters using H-shaped resonators

A new H-shaped resonator configuration is introduced for dual-band bandpass filter applications. This new design provides flexibility in controlling central frequencies and bandwidths of dual-band bandpass filters. The selectivity and the upper stopband performance of dual-band bandpass filters can be improved by virtue of the proposed H-shaped resonators. Experimental design example is given to validate this filter design theory. The proposed filters have compact size, low insertion losses and small group delay variations. The measured results show good agreement with theoretical analysis.

Compact dual-band bandpass filter with good frequency selectivity

A compact microstrip dual-band bandpass filter with controllable bandwidth for each passband and good frequency selectivity is proposed. The proposed dual-band bandpass filter has five transmission zeros. The transmission zeros are generated by each dual-mode resonator and input/output port cross-coupling. The dual-band bandpass filter application is designed for 2.4/5.2 GHz WLAN. Experimental measurements are presented to validate the theory.

Compact and High-Selectivity Microstrip Bandpass Filters Using Triple-/Quad-Mode Stub-Loaded Resonators

In this letter, a class of triple-/quad-mode stub-loaded resonators is proposed and analyzed for application in bandpass filters (BPFs). First, a pair of two identical open-ended stubs, shorter than λ/2, are tap-connected to a λ/2 resonator at two symmetrical positions with respect to its center. It results to excite three resonant modes closely to each other while producing a transmission zero above its resonant frequencies. Next, a single open-ended stub, longer than λ/2, is introduced at the center of the resonator. This arrangement is made to bring out a fourth resonant mode approaching the above three modes while causing a transmission zero below all of them. As such, a quad-mode resonator, self-contained with two transmission zeros, is theoretically constituted. Finally, the triple- and quad-pole BPFs with miniaturized size and sharpened roll-off skirts are designed and fabricated to provide an experimental validation on the predicted performances of the proposed filters.

A Tuneable Active Inductor With High Dynamic Range for Band-Pass Filter Applications

An approach for the design of high- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> active inductor (AI) with high dynamic range is presented. The proposed AI includes a passive variable phase- and amplitude-compensating network and a highly linear inverting amplifier, forming a gyrator-C architecture. The equivalent inductance and resistance values are tunable in a wide frequency range; outside the operating frequency band, the inductor equivalent resistance increases, improving signal rejection for band-pass filter applications. As a feasibility demonstration, a first-order active band-pass filter using the high- <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Q</i> active inductance has been fabricated and tested. The filter has a center frequency of 600 MHz and a measured noise figure of 11 dB with a 5-dBm 1-dB compression point and an 82-dB dynamic range.

High rejection, tunable parallel resonance in micromachined lead zirconate titanate on silicon resonators

This paper presents a micromachined lead zirconate titanate-on-silicon electromechanical resonator, tunable from series to parallel resonance, for either bandstop or bandpass filter applications. Scattering parameter measurements (9.2 V direct current (DC) bias) reveal bandstop rejection levels > 109 dB at 59.74 MHz and passband loss of 40 dB with a −20-dB bandwidth of 25 kHz (0.042%). These compare within 5-dB of the models. Parallel resonance is also observed for an alternate mechanical mode at 182.8 MHz with a 1.5 V DC bias with a rejection of 54.7 dB, a −20 dB bandwidth of 41 kHz (0.022%). This mode is tunable with the electric field to show series resonance.

Automated and adaptable quantification of cellular alignment from microscopic images for tissue engineering applications.

Cellular alignment plays a critical role in functional, physical, and biological characteristics of many tissue types, such as muscle, tendon, nerve, and cornea. Current efforts toward regeneration of these tissues include replicating the cellular microenvironment by developing biomaterials that facilitate cellular alignment. To assess the functional effectiveness of the engineered microenvironments, one essential criterion is quantification of cellular alignment. Therefore, there is a need for rapid, accurate, and adaptable methodologies to quantify cellular alignment for tissue engineering applications. To address this need, we developed an automated method, binarization-based extraction of alignment score (BEAS), to determine cell orientation distribution in a wide variety of microscopic images. This method combines a sequenced application of median and band-pass filters, locally adaptive thresholding approaches and image processing techniques. Cellular alignment score is obtained by applying a robust scoring algorithm to the orientation distribution. We validated the BEAS method by comparing the results with the existing approaches reported in literature (i.e., manual, radial fast Fourier transform-radial sum, and gradient based approaches). Validation results indicated that the BEAS method resulted in statistically comparable alignment scores with the manual method (coefficient of determination R(2)=0.92). Therefore, the BEAS method introduced in this study could enable accurate, convenient, and adaptable evaluation of engineered tissue constructs and biomaterials in terms of cellular alignment and organization.

이중 모드 공진기를 이용한 이중 대역 대역 통과 필터 설계

A compact microstrip dual-band bandpass filter with controllable bandwidth for each passband is proposed. Each passband is independently designed using two different dual-mode resonators. The proposed dual-band bandpass filter has three transmission zeros. Two transmission zeros are generated by each dual-mode resonator. An additional transmission zero is generated by input/output port coupling. The dual-band bandpass filter application is designed for 2.4/5.7 GHz WLAN. Experimental results are presented to validate theory.

Investigation of dominant sources of infrasonic wind noise in ground level microphones.

A two part project has investigated whether the pressure fluctuations (infrasonic wind noise) at the ground, as measured in an open field, can be predicted from the vertical wind velocity measured above the ground. The dominant region contributing to the pressure on the ground is calculated theoretically and displayed with contour plots. Experimentally, time dependent correlations between the measured pressure and wind velocities were done. The correlation coefficients were very low, typically between 0.08–0.15, for broadband frequencies up to 5 Hz. Cross spectrum analysis and application of octave band pass filters showed the dominant frequencies for correlations to be around 0.07–0.1 Hz, with correlation coefficients typically between 0.3–0.5. [Project funded by the US Army Space and Missile Defense Command.]

Pulsed laser deposited Y3Fe5O12 films: Nature of magnetic anisotropy I

Recently we sintered by pulsed laser deposition (PLD) technique the epitaxial Fe-deficient yttrium iron garnet (YIG) films with ferromagnetic resonance (FMR) linewidth as narrow as 0.9 Oe, the uniaxial anisotropy as high as Hu=−880 Oe, and demonstrated them feasible for magnetostatic waves band pass filter application [Manuilov et al., J. Appl. Phys. 105, 033917 (2009)]. Here we explore the origin of unusually high noncubic magnetic anisotropy. Using the angular resolved FMR spectroscopy we found that in addition to strong uniaxial anisotropy, cubic magnetic anisotropy experienced almost fivefold reduction compared to standard YIG grown by liquid phase epitaxy. Molecular field theory was employed to calculate saturation magnetization 4πMs, cubic magnetocrystalline K1, and uniaxial anisotropy Ku in garnets with Fe vacancies. The modeling utilizes crystal field parameters that we revealed from earlier published experimental data on diamagnetic ion substituted Y3Fe5O12 and Fe-substituted isomorphous diamagnetic garnets. Consistent single ion anisotropy crystal field theory perfectly fits experimentally observed high saturation magnetization, reduction in cubic, and appearance of strong uniaxial anisotropy in PLD-grown Fe-deficient YIG films. The redistribution of Fe vacancies between different magnetic sublattices was quantified and confirmed that in YIG(111) films ferric ions preferentially leave vacant octahedrally coordinated sites. Simulation of growth induced anisotropy proves the ordering of Fe3+ vacancies within octahedral sites. At equal number of available ferric ions and vacancies, the latter populate the octahedrons with distortion axis perpendicular to the film surface with the probability equal to 0.67. Deformation blockage of octahedral complexes with distortion axes directed along the film surface reduces this probability down to 0.14.