Realization Of Bandpass Filter Research Articles

Design and Synthesis of Multi-Mode Bandpass Filter for Wireless Applications

In this paper, a compact bandpass filter with improved band stop and band pass characteristics for wireless applications is built with four internal conductive poles in a single resonating cavity, which adds novel quad-resonating modes to the realization of band pass filter. This paper covers the design and testing of the S-band combline coaxial cavity filter which is beneficial in efficient filtering functions in wireless communication system design. The metallic cavity high Q coaxial resonators have the advantages of narrowband, low loss, better selectivity and high potential for power handling, as compared to microstrip filter in the application to determine the quality factor of motor oils. Furthermore, the tuning of coupling screws in the combline filter allows in frequency and bandwidth adjustments. An impedance bandwidth of 500 MHz (fractional bandwidth of 12.8%) has been achieved with an insertion loss of less than 2.5 dB and return loss of 18 dB at the resonant frequency. Four-pole resonating cavity filters have been developed with the center frequency of 4.5 GHz. Insert loss at 0 dB and estimated bandwidth at 850 MHz and a quality factor of 4.3 for the band pass frequencies between 4 and 8 GHz is seen in the simulated result.

Design and Realization of Band Pass Filter in K-Band Frequency for Short Range Radar Application

Short range radar (SRR) uses the K-band frequency range in its application. The radar requires high-resolution, so the applied frequency is 1 GHz wide. The filter is one of the devices used to ensure only a predetermined frequency is received by the radar system. This device must have a wide operating bandwidth to meet the specification of the radar. In this paper, a band pass filter (BPF) is proposed. It is designed and fabricated on RO4003C substrate using the substrate integrated waveguide (SIW) technique, results in a wide bandwidth at the K-band frequency that centered at 24 GHz. Besides the bandwidth analysis, the analysis of the insertion loss, the return loss, and the dimension are also reported. The simulated results of the bandpass filter are: VSWR of 1.0308, a return loss of -36.9344 dB, and an insertion loss of -0.6695 dB. The measurement results show that the design obtains a VSWR of 2.067, a return loss of -8.136 dB, and an insertion loss of -4.316 dB. While, it is obtained that the bandwidth is reduced by about 50% compared with the simulation. The result differences between simulation and measurement are mainly due to the imperfect fabrication process.

Suppressing In-Band Interference: A Compact Lumped-Element Bandpass Filter with Adaptive In-band Interference Suppression Capabilities

Because of today?s exceedingly crowded radio spectrum, in which multiple sources of dynamic interference can desensitize a radio's receiver, the design of bandpass filters (BPFs) with adjustable transfer function characteristics has become a critical topic of research [1]-[14]. Out-of-band interference has been traditionally addressed by increasing the filter order, but the suppression of in-band interfering signals requires more sophisticated preselect RF filtering solutions, particularly for dynamic jamming scenarios. These include the integration of tunable bandstop filters (BSFs) in front of the preselected BPF [2]-[4] or the realization of BPFs with in-band interference suppression capabilities through incorporated BPF/BSF architectures that are codesigned to miniaturize the size of the preselected RF front-end stage [5]-[11].

Hybrid Acoustic-Wave-Lumped-Element Resonators (AWLRs) for High-<formula formulatype="inline"><tex Notation="TeX">$Q$</tex> </formula> Bandpass Filters With Quasi-Elliptic Frequency Response

A new class of bandpass filters with quasi-elliptic frequency response, small physical size, and effective quality factors $(Q{\bf s}_{\bf eff})$ of the order of 1000 are presented. They are based on novel hybrid acoustic-wave-lumped-element resonator (AWLR) modules that enable the realization of bandpass filters with fractional bandwidths (FBWs) that are much larger (0.91–5.1 $k_{t}^{2}$ ) than the electromechanical coupling coefficient $(k_{t}^{2})$ of conventional acoustic wave (AW) resonator filters that exhibit FBWs between 0.4–0.8 $k_{t}^{2}$ . In addition, they exhibit $Q{\bf s}_{\bf eff}$ that are 25–50 times larger than in traditional lumped-element filter architectures. Quasi-elliptic single-pole bandpass filters (one pole and two zeros) made up of commercially available one-port surface AW resonators and surface-mount-device components are manufactured and measured at 418 MHz. Various passbands with FBW between 0.07% and 0.4% and insertion loss below 1.25 dB (i.e., $Q{\bf s}_{\bf eff}$ in the range of 1525–5150) are demonstrated. Second-order bandpass filters (two poles and four zeros) with 0.24% FBW and less than 1.15 dB of insertion loss (i.e., $Q{\bf s}_{\bf eff}$ of 4000) are also shown to improve the passband selectivity and out-of-band rejection. These filters feature dynamic stopband characteristics by tuning the position of their transmission zeros. The operating principle, theoretical analysis, and design guidelines of the AWLR module, as well as a comparison with traditional all-AW ladder-type filters, are also reported. An original and rather simple $RLC$ -circuit equivalent of AW resonators that facilitates the incorporation of spurious modes into a simple Butterworth–Van-Dyke model for a more accurate synthesis of AWLR-based filters is extracted from measured two-port S-parameters.

Design of a unit composite right/left-handed cell based bandpass filter with floating slot approach and suppression of spurious using defected microstrip structures

This paper presents the construction of a unit composite right/left-handed cell using hairpin microstrip coupled line circuits. To get the high coupling in comparison to conventional edge coupled microstrip line, the floating slot on the ground plane is used here. Two basic configurations named after short---open---short (SOS) the open---short---open (OSO) model are studied for the realization of band pass filter. The floating ground equalizes the even and odd mode phase velocities and solves the difficulties arises in the fabrication process as it relaxes the requirements on physical dimensions like coupled gaps between lines. The hairpin structure makes the filter structure more compact in size. Defected microstrip structure on the feed line suppresses the spurious response and provides a good stopband performance. Finally a bandpass filter having fractional bandwidth of 70.83 % for OSO model and 44.05 % for SOS model are obtained. Those filters have wide application in modern wireless communication system.

Wide-Band Bandpass Filter Using CRLH Transmission Line and Floating Slot Approach

This paper presents construction of a composite right/left-handed (CRLH) transmission line (TL) using microstrip coupled lines. For getting high coupling in comparison to conventional edge coupled microstrip line, the floating slot in the ground plane is used. Two configuration named as SOS(shortopen-short) the OSO(open-short-open) model are studied for realization of band pass filter. The floating ground equalizes the even and odd mode phase velocities and solves the difficulties arised in the fabrication process as it relaxes the required physical dimensions like coupled gaps between lines. Finally a bandpass filter having bandwidth of 56.7% and selectivity of 40dB/GHz has been designed using OSO model and the experimental results are verified with EM simulated results.

A compacted CMOS K‐band bandpass filter using meandering thin film microstrip and UC‐PBG structures

AbstractA compacted CMOS K‐band bandpass filter incorporating meandering thin film microstrip and defective uniplanar compact photonic bandgap (UC‐PBG) slow‐wave structures for size reduction are presented. Benefited from the multilayer metal technology of the standard 0.18‐μm CMOS process, meandering thin film microstrip and broadside‐coupled structures with large coupling degree are properly constructed to realize bandpass filters with small insertion loss. The slow‐wave effect of UC‐PBG structure is investigated and a center frequency drop of 14% is achieved by the use of UC‐PBG ground. A 3.6‐dB loss 18‐GHz filter with two transmission poles has been designed and implemented in standard 0.18‐μm CMOS technology and only with an area of 0.34 mm2. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 871–874, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24180

Wideband Microstrip Bandpass Filter Based on EBG Concept

A periodically loaded ultra wideband (UWB) bandpass filter based on the electromagnetic band-gap (EBG) concept is presented. Compact wideband filters with steep transition bands can be designed easily using this novel methodology. Unit cells in the EBG circuit model are realized by capacitive and inductive parallel loading of a transmission line. These unit cells are cascaded to realize bandpass filters whose bandwidth depends on the reactive loading of unit cells. The number of unit cells determines the steepness of the band edges of the filter. The main advantage lies in the fact that the size of unit cells can be small because electrical length of transmission line segments in unit cells can be chosen arbitrarily, hence the final filter structure becomes small in size. A microstrip filter with 60% bandwidth is designed and the physical size is compared with a conventional wideband bandpass filter designed with quarter wavelength admittance inverters.

Bandpass filters using dual-mode and quad-mode Mobius resonators

Compact bandpass filters are being developed using Mobius wire-loaded cavity resonators. Initial results on tuned filters indicate that excellent filter characteristics can be attained in devices that are significantly smaller than traditional wire-loaded cavity technologies. A novel quad-mode Mobius resonator is presented which occupies the same volume as a dual-mode Mobius resonator. A four-pole bandpass filter is demonstrated using a single quad-mode Mobius resonator. Precisely controlled dielectric loading of dual-mode Mobius wire resonators has been implemented to realize bandpass filters. Two-pole and four-pole bandpass filters are demonstrated using one and two dual-mode dielectric-loaded Mobius resonators, respectively.

Current-differencing band-pass filter realization with application to high-frequency electronically tunable low-supply-voltage current-mirror-only oscillator

A new method of realizing a band-pass filter by taking the difference between the outputs of two unequal bandwidth low-pass filters is proposed. The resulting band-pass filter is particularly suitable for implementation in current-mode forms. Such a current-differencing band-pass filter will then be applied to realize a new high-frequency, low-supply-voltage, current-mirror-only oscillator, possessing wide electronically tunable frequency range. A new simple and convenient loop-gain control method using the Early effect associated with the output transistors of the current-mirrors has also been employed to control the oscillation amplitude.

Resonance scattering by a dielectric cylinder in a rectangular waveguide below cut-off

Scattering by a dielectric cylinder in a rectangular waveguide excited at frequencies below cut-off for the principal mode has been analysed. The resonance frequency change with the cylindrical post positioned perpendicular to the axis of the waveguide has been calculated. The lowest resonance of the dielectric cylinder can be used for microwave band-pass filter realization. The calculated results show good agreement with experiment.

The implementation and applications of current conveyors

The realization of current conveyors using op amps has been discussed, implemented and experimentally verified so that they can be integrated on a single chip. Nowadays, an important criterion of success for a circuit is that it should be easily integrable. Contemporary circuits have been tested and the best one is analysed theoretically and experimentally verified. A novel band-pass filter realization and a new general circuit for realizing oscillators have been proposed as applications and experimentally verified along with theoretical analysis and other considerations.

Comments on "High selectivity grounded capacitor bandpass and low-pass filters using the amplifier pole"

Three recently proposed grounded capacitor active filters using the amplifier pole have been compared. Some limitations of these circuits for realizing bandpass filters at low frequencies, due to the finite ω a of the operational amplifier, are discussed. These circuits are also compared with other input-capacitor based bandpass filters.

From switched-capacitors to digital filters

Digital filters have been realized with inexpensive reverse switched capacitors and expensive special purpose digital computers. Analysis shows that the semi-null inherent in any switched capacitor can be eliminated with an analog-to-digital converter realization which is intermediate in cost. The main emphasis is on band-pass filter realization by means of the overlapping spectra method and a preferred ordering of the cascaded filter sections. Band-rejection filter realization is considered for completeness.

A novel bandpass filter using the amplifier pole

A new bandpass filter using the operational-amplifier pole and a single external capacitor has been described. It has been shown that the circuit can realize infinite pole-frequency Q product. The applicability of the circuit for realizing bandpass filters and oscillators has been investigated.

Active Realization of Band-pass Filter for Channel Translating Equipment

Active realization of the Channel Band-pass Filter by inductance simulation has been described. Usefulness of positive impedance converter networks (PIC) for inductance simulation has been demonstrated. A method for realizing floating inductor accurately has been presented. Test results taken on a laboratory model of the active filter have been utilized to show its superior performance over the conventional inductor-capacitor type of filter.

Acoustic Surface Wave Diffraction and Beam Steering

Abstract : The report contains a detailed description of diffraction in acoustic surface wave devices. This source of loss is highly important in the design and realization of bandpass filters, long time delay lines and other devices for electronic sensors and communications systems. A complete review of acoustic surface wave diffraction on anisotropic substrates is presented. Full experimental verification of theory is provided. Complete computer program listings and descriptions are provided. The limits of applicability of the parabolic velocity surface theory are quantitatively delineated. Universal diffraction loss design curves are given for all parabolic materials. A limitation in the use of the exact angular spectrum of waves theory occurs for materials having a power flow angle slope approximately - 1 unless the velocity surfaces are very accurately known. Both YZ LiNbO3 and 16-1/2 degree double rotated LiNbO3 fall in this category. Approximate diffraction loss design curves are given for YZ LiNbO3. A complete tabular summary of all important material properties affecting acoustic surface wave device design is included. (Author)

Synthesis of multibandpass numerical filters

The problem of low-pass to multibandpass transformation of numerical filters is considered. Properties of frequency transformations are studied and, based on these, a general design procedure is outlined which may be used for obtaining filters with any number of passbands. The procedure is illustrated by means of a ten passband example. A canonic form for realizing bandpass filters is also discussed.