Spurious Resonances Research Articles

Defected‐ground coupled microstrip lines bandpass filter with suppressed spurious resonances

AbstractDefected‐ground coupled microstrip lines (DCL) bandpass filter is proposed. The length of the proposed filter is quarter the length of conventional coupled‐line filter and it has a wide stopband and suppressed spurious resonances up to 4f0, where f0 is the filter central frequency. Five hundred and fifty megahertz single‐section and two‐section DCL filters were designed and fabricated. Simulations and measurements show that the rejection levels of the spurious resonances at 2f0, 3f0 as well as 4f0 are better than −11 and −14 dB for single‐section DCL and double‐section DCL, respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2038–2039, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22590

Wavenumber domain analysis of two-dimensional SAW images captured by phase-sensitive laser probe system

This paper is aimed at demonstrating how the wavenumber domain analysis of two-dimensional (2-D) images captured by phase-sensitive laser probe systems is applied in the characterization of RF SAW devices. Effectiveness is demonstrated through the selective characterization of spurious resonance modes and scattered, nonguided modes appearing in SAW resonators.

Novel bandpass filter with wide stopband using double‐sided parallel‐strip line

AbstractA novel bandpass filter using double‐sided parallel‐strip line (DSPSL) is proposed in this paper. Based on the differential characteristics of DSPSL, the proposed filter has a wide stopband up to the third spurious resonance frequency. Also, this filter can achieve high power‐handling capability because the linewidth of DSPSL is wider than that of microstrip with the same characteristic impedance. A demonstration filter was designed, fabricated, and measured. Theoretical and experimental results are presented and show good agreement. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 722–724, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22244

Design of a Broadband Parallel-Coupled Microstrip Filters without Spurious Resonances

A design of parallel-coupled microstrip bandpass filters without spurious resonance is presented. Two different techniques are used to eliminate this response at twice the passband frequency (2fo). The first one is based on usage of suspended substrate, while the second is carried out by shorting the parallel-coupled lines to the ground plane through two shorting walls. The numerical results show that a broadband filter can be obtained by the suppression of the spurious response. The finite difference time domain (FDTD) with the perfect matched layer (PML) is used in the present analysis. The obtained results are compared with the available published data and good agreements are found.

A Two-Stage SIR Bandpass Filter With an Ultra-Wide Upper Rejection Band

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

A COMPACT SQUARE LOOP DUAL-MODE BANDPASS FILTER WITH WIDE STOP-BAND

A new dual-mode microstrip bandpass filter with wide stop-band is presented using the square loop resonator with treeshaped patches attached to the four inner corners of the loop. The mode splitting is realized by introducing a small cut locating at a 45◦ offset from its two orthogonal modes. It is shown that the dual-mode filter has a wide stop-band including the first spurious resonance frequency. The center frequency can be tuned. Moreover, the proposed filter has a smaller size compared with conventional dualmode bandpass filters at the same central frequency.

Design of Matching Circuits for Microstrip Triplexers Based on Stepped-Impedance Resonators

New matching circuits for microstrip triplexers are proposed based on half-wavelength tapped-connected (or fed) stepped-impedance resonators. The stepped-impedance resonators play important roles for the matching circuits, either to serve as a through pass at the center frequency of a bandpass filter or to provide a short circuit at the center frequency of another bandpass filter. First, three tapped-connected stepped-impedance resonators together with suitable branch transmission lines are utilized to develop the matching circuits for a microstrip triplexer. The design procedure for these matching circuits is much simpler than that for the conventional triplexer structures due to the use of tapped-connected stepped-impedance resonators. Second, to reduce the number of stepped-impedance resonators and to improve the spurious resonances associated with the proposed matching circuits, modified matching circuits for the triplexer are also proposed. Agreement between measured and simulated results is observed and supports the usefulness of the design procedure

Dynamics of three-layer bars

We study vibrations of a three-layer bar under local, pulse, and resonance loads of rectangular and sinusoidal forms. Bernoulli hypotheses are used for describing the kinematics of bearing layers. For rigid compressible filler, the elastic-theory relationships with linear approximation of the function of displacement of its points vs. the transverse coordinate z hold good. Analytical solutions to the problems have been obtained, numerically and comparatively analyzed. The probability of a spurious resonance occurrence is discussed.

Analysis of the response to orographic forcing of a time‐staggered semi‐Lagrangian discretization of the rotating shallow‐water equations

AbstractA recently proposed time‐staggered semi‐Lagrangian discretization of the unforced rotating shallow‐water equations is extended to include orographic forcing. Linear analysis shows that, as for traditional semi‐implicit semi‐Lagrangian schemes, it is also susceptible to spurious orographic resonance for large Courant numbers. A solution is proposed which, as shown by further linear analysis, addresses spurious orographic resonance whilst also maintaining computational stability. © Crown copyright, 2006. Royal Meteorological Society

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.

A Bandpass Filter Design Using Half-Wavelength Stepped Impedance Resonators With Internal Couplings

We propose a new type of microstrip half-wavelength (lambda/2) stepped impedance resonator (SIR) for use in bandpass filter (BPF) designs. This lambda/2 SIR has an internal coupling section that can be used to generate a coupling coefficient in the filter design in addition to couplings between SIRs. It also contains additional stepped impedance lines that shift and suppress the lowest even-mode resonance frequencies to more than what can be achieved by conventional lambda/2 SIRs. Moreover, a transmission zero is generated close to its fundamental resonance frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ) which can be used in definition of the filter response. A fourth-order microstrip BPF with 10% bandwidth was constructed using two of the proposed lambda/2 SIRs with a stepped impedance ratio (R) of 0.528. The experimental result shows that the filter can achieve low in-band loss and out-of-band attenuation of 52.6dB up to 3f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> . The lowest spurious resonance frequency is shifted to 3f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> as opposed to 2.5f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> in conventional lambda/2 SIRs with the same R value

Development of fast-scanning laser probe system based on knife-edge method for diagnosis of RF surface acoustic wave devices

This paper describes the development of a high-speed laser probe system for surface acoustic wave (SAW) devices. A fast scanning rate of 2.5 kS/s is realized by continuous stage translation and successive acquisition of the detector output by a high-speed data-logger. Trigger pulses are generated from the output of a high-precision linear-scale installed in the translation stage and fed to the data-logger for the synchronization with the stage movement. The phase-sensitive, knife-edge method is used for the optical detection. This makes the system very unsusceptible to low-frequency mechanical vibration caused by the fast stage translation. The system is applied for the characterization of spurious resonance modes in SAW devices. In conjunction with skillful use of image processing in wavenumber domain, it is shown how the present system is effective in the diagnosis and development of SAW devices.

Synthesis of capacitive-coupled dual-behavior resonator (CCDBR) filters

The two topologies and associated syntheses described here are dedicated to the design of capacitive-coupled dual-behavior resonator filters. The technique is based on the coupling of adjacent dual-behavior resonators (DBRs). The aim is to control the spurious resonances associated to classical DBR filters. In the first coupling technique, the inverter is replaced with an equivalent scheme composed of a set of three capacitors, i.e., a positive capacitor associated with two negative ones in parallel on both sides. The second technique relies on the same principle, but two equivalent schemes are moved along each stub of the resonators; the capacitance is then calculated by considering the position of the coupling effect on the stub and the value of the inverter. In both cases the synthesis is totally defined. In order to validate this concept, capacitive-coupled DBR filters and classical filters were designed on alumina substrate so as to compare simulation and experimental data

Piezocomposite ultrasonic transducer for high-frequency wire-bonding of microelectronics devices

Piezocomposite ultasonic transducers for high-frequency microelectronics wire bonding have been developed to alleviate the intrinsic mode coupling and high mechanical quality factor ( Q m) in piezoceramic transducers. In this paper, a 136 kHz transducer fabricated using lead zirconate titanate (PZT)/epoxy 1–3 piezocomposite rings with 77 μm epoxy width and 0.89 PZT volume fraction is presented, together with a PZT piezoceramic transducer of similar structure. With the guide of a finite-element modal analysis, the nature of most experimental resonance modes in the transducers is identified. The low lateral coupling of the composite rings effectively suppresses the non-axial and many other spurious resonances in the composite transducer, retaining only the axial-mode resonances. Due to the effect of epoxy damping, the composite transducer exhibits a 2.4-times reduction in Q m to a desired low value of 296. This transducer has good potential to be used in commercial wire bonders for enabling high-frequency wire-bonding technology.

A two‐pole 900/1800‐MHz microstrip filter for dual‐band applications

AbstractA two‐pole 900/1800‐MHz dual‐band bandpass filter using microstrip open‐loop resonators is proposed. Dual‐band characteristics are obtained by using the fundamental and first spurious resonance of the resonators. Both the internal and external couplings of the filter are appropriately designed to simultaneously satisfy the dual‐band requirements. The measured filtering characteristics of the designed filter agree well with the simulated responses. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1388–1391, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21639

A wideband balun and vertical transition between conductor-backed CPW and parallel-strip transmission line

A wideband vertical transition between conductor-backed coplanar waveguide (CBCPW) and parallel-strip (PS) transmission line is presented. By choosing the same widths for the two conductor strips comprising the PS transmission line, the transition performs unbalanced-to-balanced transformation as well. Back-to-back configurations of the transition have been realized and their transmission, reflection, and direct-coupling characteristics have been measured. It is shown that the placement of vias connecting the top and the bottom grounds of the CBCPW along the entire gap between the truncated center conductor and the ground is crucial in preventing spurious resonances of the CBCPW structure. The fabricated back-to-back transition features low insertion loss over the 28:1 frequency range that has been tested.

Wide-stopband microstrip bandpass filters using dissimilar quarter-wavelength stepped-impedance resonators

Wide-stopband and compact microstrip bandpass filters (BPFs) are proposed using various dissimilar quarter-wavelength (/spl lambda//4) stepped-impedance resonators (SIRs) for multiple spurious suppression. The use of /spl lambda//4 SIRs is essential in widening the filter stopband and reducing the circuit size. By properly arranging the individual /spl lambda//4 SIR, which has the same fundamental resonance frequency f/sub 0/, but has different spurious (harmonic) resonance frequencies, and also carefully misaligning the maximum current density nodes, several higher order spurious resonances may be suppressed so that a BPF with wide stopband may be realized. In this study, the basic concept of multiple spurious suppression is demonstrated by thoroughly investigating the spurious characteristics of the fourth-order interdigital BPFs, which consist of two different types of /spl lambda//4 SIRs. To widen the rejection bandwidth, the fourth-order coupled-resonator BPFs based on three and four different types of /spl lambda//4 SIRs are implemented and carefully examined. Specifically, a very wide-stopband microstrip BPF composed of four dissimilar /spl lambda//4 SIRs is realized and its stopband is extended even up to 11.4f/sub 0/ with a rejection level better than 27.5 dB.

A planar bandpass filter design with wide stopband using double split-end stepped-impedance resonators

In this paper, we propose a compact planar bandpass filter design with wide stopband. The double split-end quarter-wave-length (/spl lambda//4) resonator is introduced to reduce the resonator size while providing additional transmission zeros. Optimal split-end length is determined to provide transmission zeros that attenuate the two lowest spurious resonance frequencies. The singly loaded quality factor (Q/sub si/) of the optimal-length /spl lambda//4 stepped-impedance resonator (SIR) is also analytically derived. Using the proposed technique to design an Nth-order filter, N+1 controllable transmission zeros are generated and used to suppress spurious frequency responses. The experimental design shows that the sixth-order filter can provide a very broad stopband of 8.5 times the fundamental frequency with at least 37.8 dB of attenuation using the SIRs with a stepped-impedance ratio (R) of 0.528.

Novel compact net-type resonators and their applications to microstrip bandpass filters

Novel compact net-type resonators and their practical applications to microstrip bandpass filters have been presented in this paper. Three kinds of filters are designed and fabricated to demonstrate the practicality of the proposed compact net-type resonators. In addition, by adjusting the structural parameters of the net-type resonators, the spurious frequencies can be properly shifted to higher frequencies. As a result, a three-pole Chebyshev net-type resonator filter with a fractional bandwidth (FBW) of 6.8% has a spurious resonance of up to 4.1f/sub 0/, and it has more than 80% size reduction in comparison with the conventional U-shaped resonator filter. A four-pole quasi-elliptic net-type resonator filter with a FBW of 3.5% has a spurious resonance of up to 5f/sub 0/, and it has approximately 67% size reduction in comparison with the cross-coupled open-loop resonator filter. A three-pole trisection net-type resonator filter with a FBW of 4.7% has a spurious resonance of up to 6.5f/sub 0/, and its size is reduced by 68% in comparison with the trisection open-loop resonator filter. Consequently, each of the designed filters occupies a very small circuit size and has a good stopband response. The measured results are in good agreement with the full-wave simulation results by IE3D.

Stabilized FEM‐BEM Coupling for Helmholtz Transmission Problems

We consider time‐harmonic acoustic scattering at a nonsmooth penetrable object and coupled boundary element finite element schemes for its numerical simulation. Straightforward coupling approaches are haunted by instabilities at wave numbers related to interior resonances, the so‐called spurious resonances. A remedy is offered by adopting the idea underlying the widely used combined field integral equations. We apply it in the form of modified trace operators. These will also feature regularizing operators to offset the lack of compactness of the double‐layer potential integral operators on nonsmooth surfaces. Calderón projectors can be defined based on the modified trace operators. Thus, Costabel’s approach to the symmetric coupling of domain variational formulations and boundary integral equations carries over. The modified traces guarantee uniqueness of solutions of the coupled problem, whereas regularization ensures coercivity. From this we immediately concludeasymptotic quasi‐optimality of a combined finite element and boundary element Galerkin discretization for all frequencies.