Showing papers on "Stopband published in 2016"
TL;DR: In this article, a compact reconfigurable (bandstop/bandpass) and frequency-tunable structure based on S-shaped split-ring resonators (S-SRRs) is proposed.
Abstract: This paper proposes a compact reconfigurable (bandstop/bandpass) and frequency-tunable structure based on S-shaped split-ring resonators (S-SRRs). It is known that an S-SRR coupled to a coplanar waveguide (CPW) provides a stopband in the transmission characteristic of the line. It is shown here that this behavior of the S-SRR can be switched between fundamental resonance and second harmonic response by introduction of a p-i-n diode in the center segment of the S-SRR. Alternatively, if the S-SRR is loaded with a varactor diode instead of a switch, the frequency of the stopband can be continuously tuned from the S-SRRs fundamental resonance frequency to its second harmonic. Furthermore, it is shown that if a pair of shunt p-i-n diodes are introduced across the slots of the host CPW, the structure can be reconfigured from a bandstop to a bandpass structure. Thus, the proposed resonator structure can be used as the building block of reconfigurable (bandstop/bandpass) filters with tunable operating frequency. Finally, to demonstrate a practical application of the proposed structure, an ultrawideband antenna with a tunable band notch is designed and experimentally validated.
123 citations
TL;DR: In this paper, a rectangular filtering dielectric resonator antenna (FDRA) with low profile, wide bandwidth, and high gain is investigated in this communication, and a modified DRA fed by a pair of separated slots is proposed to further enhance the gain by 4$ dB.
Abstract: A rectangular filtering dielectric resonator antenna (FDRA) with low profile, wide bandwidth, and high gain is first investigated in this communication. It is fed by a microstrip-coupled slot from bottom, with open stub of the microstrip feedline elaborately designed to provide two radiation nulls at band edges for a filtering function. A separation is introduced in the slot to provide a good suppression level in lower stopband, while two parasitic strips are parallelly added to the microstrip feedline to offer good suppression in the upper stopband, and consequently, a compact FDRA with a quasi-elliptic bandpass response is obtained without involving specific filtering circuits. Based on the design, a modified DRA fed by a pair of separated slots is proposed to further enhance the gain by $\sim 4$ dB. A prototype operating at 5 GHz has been fabricated and measured for demonstration. The reflection coefficient, the radiation pattern, and the antenna gain are studied, and reasonable agreement between the measured and simulated results is observed. The prototype has a 10-dB impedance bandwidth of 20.3%, an average gain of 9.05 dBi within passband, and an out-of-band suppression level of more than 25 dB within a wide stopband.
97 citations
TL;DR: In this paper, a lumped element equivalent circuit is proposed and analyzed in detail for microstrip lines with pairs of complementary split-ring resonators (CSRRs), and a proof-of-concept of a differential sensor is proposed.
Abstract: This letter is focused on the modeling, analysis, and applications of microstrip lines loaded with pairs of electrically coupled complementary split-ring resonators (CSRRs). Typically, these epsilon-negative (ENG) metamaterial transmission lines are implemented by loading the line with a single CSRR (etched beneath the conductor strip) in the unit cell. This provides a stopband in the vicinity of the CSRR resonance. However, by loading the line with a pair of CSRRs per unit cell, it is possible to either implement a dual-band ENG transmission line (useful, for instance, as a dual-band notch filter), provided the CSRRs are tuned at different frequencies, or to design microwave sensors and comparators based on symmetry disruption (in this case by using identical CSRRs and by truncating symmetry by different means, e.g., asymmetric dielectric loading). The design of these CSRR-based structures requires an accurate circuit model able to describe the line, the resonators, and the different coupling mechanisms (i.e., line-to-resonator and inter-resonator coupling). Thus, a lumped element equivalent circuit is proposed and analyzed in detail. The model is validated by comparison to electromagnetic simulations and measurements. A proof-of-concept of a differential sensor for dielectric characterization is proposed. Finally, the similarities of these structures with coplanar waveguide transmission lines loaded with pairs of SRRs are pointed out.
90 citations
TL;DR: In this article, the authors examined the elastic wave propagation properties of metamaterials with locally resonant membranes arranged in a square array, and the macroscopic dynamical properties of the resulting periodic structures depend on the resonant properties of substructures.
Abstract: Vibration band gaps and elastic wave propagation are examined in the metamaterial plates manufactured with periodic locally resonant membranes arranged in a square array. Periodic metamaterials exhibit unique dynamic characteristics stemming from their ability to act as mechanical filters for wave propagation. As a result, waves propagate along the periodic cells only within specific frequency bands called the pass bands, while being blocked within other frequency bands called the stop bands. The proposed metamaterial plates are equipped with sources of local resonances which act as local absorbers of mechanical vibrations. The macroscopic dynamical properties of the resulting periodic structures depend on the resonant properties of substructures which contribute to the rise of interesting effects such as broad stop band characteristics that extend to lower frequencies. Externally excited piezoelectric polyvinylidene difluoride membranes are used to support the local resonators. The stiffness of the piezo...
85 citations
TL;DR: A multi-objective optimization technique is used for controlling some filter specifications, which are the transition bandwidth, the stop band frequency gain and the maximum allowable peak in the filter pass band.
Abstract: This paper presents three different optimization cases for normalized fractional order low-pass filters (LPFs) with numerical, circuit and experimental results. A multi-objective optimization technique is used for controlling some filter specifications, which are the transition bandwidth, the stop band frequency gain and the maximum allowable peak in the filter pass band. The extra degree of freedom provided by the fractional order parameter allows the full manipulation of the filter specifications to obtain the desired response required by any application. The proposed mathematical model is further applied to a case study of a practical second- generation current conveyor (CCII)-based fractional low-pass filter. Circuit simulations are performed for two different fractional order filters, with orders 1.6 and 3.6, with cutoff frequencies 200 and 500 Hz, respectively. Experimental results are also presented for LPF of 4.46 kHz cutoff frequency using a fabricated fractional capacitor of order 0.8, proving the validity of the proposed design approach.
78 citations
TL;DR: In this article, a compact wideband four-way filtering PD is presented, which includes a pair of looped coupled-line structures to provide the needed power division to four output ports.
Abstract: A compact wideband four-way filtering PD is presented. The structure of the proposed device includes a pair of looped coupled-line structures to provide the needed power division to four output ports. Moreover, a pair of short-ended coupled-line stubs is used to introduce multiple transmission poles and transmission zeros for a sharp cut-off of the passband and high upper-stopband rejection. A detailed design procedure is shown to determine the initial design parameters. A prototype is designed, simulated and measured experimentally. The measured results show 56.5% bandwidth centered at 1.5 GHz with more than 15 dB upper-stopband rejection up to 4.15 GHz, more than 13 dB in-band isolation, and 15 dB return loss at all output ports.
73 citations
TL;DR: In this paper, a continuous-wave (CW) operation of gallium nitride (GaN)-based vertical-cavity surface-emitting lasers (VCSELs) fabricated by epitaxial lateral overgrowth (ELO) using dielectric distributed Bragg reflectors (DBRs) as masks for selective growth was achieved.
Abstract: We have achieved continuous-wave (CW) operation of gallium nitride (GaN)-based vertical-cavity surface-emitting lasers (VCSELs) fabricated by epitaxial lateral overgrowth (ELO) using dielectric distributed Bragg reflectors (DBRs) as masks for selective growth. The GaN VCSELs exhibited CW operation at a wavelength of 453.9 nm, and the maximum output power was 1.1 mW, which is the highest value reported to date. GaN-based materials have presented challenges for obtaining DBRs with high reflectivity and a wide stopband, precise control of the cavity length and a lateral confinement structure to provide laser operation. The proposed VCSEL is immune to these concerns. Its two dielectric DBRs were obtained free from cracks. A high reflectance of more than 99.9% and a stopband with a width of 80–97 nm were obtained for both DBRs. The cavity length was controlled by epitaxial growth to as short as 4.5 µm. An ITO contact electrode on p-type GaN, which is required for a lateral confinement structure, showed electrical reliability under a high current density of 59.6 kA cm−2. The present data demonstrate that the fabrication process adopted here overcomes the shortcomings that have prevented the widespread use of GaN-based VCSELs.
71 citations
TL;DR: In this paper, a power divider with filtering function as well as wide stopband is presented. But the performance of the proposed method is limited by the fact that it requires high power consumption.
Abstract: A novel filtering power divider with wide stopband is presented in this letter. It utilizes four coupled quarter- wavelength resonators to obtain dual functions. Discriminating coupling is applied to the input and output feed lines and resonators, which not only to provide suitable coupling strength but also to suppress $3f_{0}$ and $5f_{0}$ ( $f_{0}$ is the operating frequency). A resistor is connected at the two open-ends of the input feed line to obtain high isolation. Transmission zeros are generated near the passband edges, resulting in high selectivity. For demonstration, a power divider with filtering function as well as wide stopband is implemented. Good agreement between the prediction and measurement validates the proposed method.
70 citations
TL;DR: In this article, a microstrip dual-band filtering power divider (FPD) is presented, in which a proper coupling topology between the short-ended microstrip line and two multi-mode resonators is constructed, and good isolation is attained by installing an isolation resistor between the resonators.
Abstract: A novel microstrip dual-band filtering power divider (FPD) is presented in this letter. By introducing a proper coupling topology between the quarter-wavelength ( $\lambda $ /4) short-ended microstrip line and two multi-mode resonators, the dual-band FPD is constructed. Meanwhile, good isolation of this FPD is attained by installing an isolation resistor between the resonators. Additionally, two $3\lambda $ /4 open-ended stubs are attached in the output coupled lines to improve its frequency selectivity and obtain a wide upper stopband. For validation, a prototype FPD operating at 1.57 and 2.89 GHz is designed, fabricated and measured. Both the simulated and measured results are in good agreement. Results indicate that the proposed FPD exhibits not only a sharp frequency selectivity and good harmonic suppression with the help of the six inherent transmission zeros, but also better than 21 dB isolation within the entire dual operation bands.
66 citations
TL;DR: With the introduction of the short-circuit stubs shunted at the output ports and the coupled lines with the open-circuits stubs, the ultra-wide stopband can be implemented more efficiently, thus resulting in five transmission zeros from 2 to 6 GHz.
Abstract: In this paper, a wideband filtering power divider (PD) with ultra-wideband harmonic suppression and isolation is proposed. The dual coupled-line sections are embedded to the conventional quarter-wavelength transmission lines, which helps to extend the passband of the PD. With the introduction of the short-circuit stubs shunted at the output ports and the coupled lines with the open-circuit stubs, the ultra-wide stopband can be implemented more efficiently, thus resulting in five transmission zeros from 2 to 6 GHz. Furthermore, the improved isolation structure with series connected a resistor and a capacitor can be utilized to realize the ultra-wide isolation frequency band. Using a single resistor between two output ports, we have achieved an excellent in-band isolation. For demonstration, a wideband filtering PD operating at 1 GHz with a 20-dB bandwidth of 50% and an ultra-wide stopband better than 20 dB from 2 to 6 GHz is designed, fabricated, and measured. The measured results agree well with the anticipation.
56 citations
TL;DR: In this paper, a pair of coupled stepped-impedance resonators and its use to build single and dual-band bandpass filter (BPF) is presented, where the adopted resonators are coupled at the two open-ended edges.
Abstract: A pair of coupled stepped-impedance resonators and its use to build single- and dual-band bandpass filter (BPF) is presented. To that end, two symmetrical stepped-impedance resonators with two embedded coupled-line sections are used. The adopted resonators are coupled at the two open-ended edges. The first even-mode resonant mode can be suppressed or excited based on whether it is required to realize a single- or dual-band response. Sharp passband selectivity and stopband harmonic suppression are achieved due to the existence of multiple transmission zeros. For verification, single- and dual-band filters using the proposed resonator are designed, fabricated and tested. The experimental results show a passband of 2.34–2.62 GHz (centered at 2.45 GHz for WLAN system), less than 1.5 dB insertion loss for the single-band filter; the dual-band design has two passbands ranged from 2.28–2.67 GHz and 3.35–3.63 GHz with less than 1.2 dB insertion loss for WLAN and WiMAX systems.
TL;DR: In this paper, a 3-dB planar wideband power divider with an ultra-wide stopband and isolated frequency band is proposed, where the quasi-coupled lines are adopted.
Abstract: A 3-dB planar wideband power divider with an ultra-wide stopband and isolated frequency band is proposed. In order to extend the passband, the quasi-coupled lines are adopted. Moreover, the open and shorted stubs added at the input and output ports, respectively, can increase the bandwidths of the passband and stopband. Furthermore, in order to broaden the isolated frequency band, the impedance $Z _{\mathrm {iso}}$ with the series connected resister and capacitor on the right side of the middle coupled line is adopted. The detailed derivation is proposed as well. In addition, this power divider is fabricated on the substrate Rogers RO4003C with a compact size of 15.19 mm $\,\times \,11.4$ mm.
TL;DR: In this paper, a compact ultra-wideband (UWB) bandpass filter (BPF) is presented, which can exhibit an UWB response from 3.1 to 9.9 GHz with low insertion loss (IL) of 0.8 dB and an extremely broad stopband region from 10.9 to 25.1 GHz with high rejection level of 20 dB.
Abstract: This letter presents a design of a compact ultra-wideband (UWB) bandpass filter (BPF), which can exhibit an UWB response from 3.1 to 9.9 GHz with low insertion loss (IL) of 0.8 dB and an extremely broad stopband region from 10.9 to 25.1 GHz with high rejection level of 20 dB. This UWB BPF is simply constructed by using only one single-stage parallel-coupled line and two rectangular stub resonators. In this design, the rectangular stub resonators provide an exciting mode to enhance the desired UWB response and also create tunable transmission zeros to extend a wide stopband by controlling the impedance ratio $(R)$ properly. The filter was fabricated and measured to verify the design concept.
TL;DR: The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.
Abstract: A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz. In the passband, the reflection coefficient is less than -10 dB, and the transmission loss is around 3 dB; in the stopband, the reflection coefficient is -2 dB, and the transmission coefficient is less than -30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.
TL;DR: In this paper, a distributed Bragg reflector (DBR) was proposed to reuse the escaped luminescence at the front surface by utilizing a photonic band-stop filter that reflects photons in the luminophore's emission range while transmitting those in its absorption range.
Abstract: Escape cone loss is one of the primary limiting factors for efficient photon collection in large-area luminescent solar concentrators (LSCs). The Stokes shift of the luminophore, however, opens up an opportunity to recycle the escaped luminescence at the LSC front surface by utilizing a photonic band-stop filter that reflects photons in the luminophore’s emission range while transmitting those in its absorption range. In this study, we examine the functional attributes of such photonic filter designs, ones realized here in the form of a distributed Bragg reflector (DBR) fabricated by spin-coating alternating layers of SiO2 and SnO2 nanoparticle suspensions onto a supportive glass substrate. The central wavelength and the width of the photonic stopband were programmatically tuned by changing the layer thickness and the refractive index contrast between the two dielectric materials. We explore the design sensitivities for a DBR with an optimized stopband frequency that can effectively act as a top angle-res...
TL;DR: In this paper, a microstrip filtering power divider (FPD) with good isolation performance and harmonic suppression is presented by replacing a simple resistor with a novel distributed stepped-impedance resonator network, better isolation and wider stopband are simultaneously attained.
Abstract: A microstrip filtering power divider (FPD) with good isolation performance and harmonic suppression is presented. By replacing a simple resistor with a novel distributed stepped-impedance resonator network, better isolation and wider stopband are simultaneously attained. A transmission-matrix-based analysis method is then extensively described to determine the circuit geometrical parameters at the synthesis level by facilitating the incorporation of design indexes and structure dimension. A prototype FPD is designed, fabricated and measured. The proposed FPD exhibits a center frequency of 2.2 GHz ( $\text {f}_{0}$ ) with the isolation better than 17dB within the entire passband and a stopband extended to 12 GHz (5.45f0).
TL;DR: An optimal design of two-dimensional finite impulse response (2D FIR) filter with quadrantally even symmetric impulse response with fractional derivative constraints (FDCs) using HPSO-GSA is presented.
Abstract: In this article, an optimal design of two-dimensional finite impulse response (2D FIR) filter with quadrantally even symmetric impulse response using fractional derivative constraints (FDCs) is presented. Firstly, design problem of 2D FIR filter is formulated as an optimization problem. Then, FDCs are imposed over the integral absolute error for designing of the quadrantally even symmetric impulse response filter. The optimized FDCs are applied over the prescribed frequency points. Next, the optimized filter impulse response coefficients are computed using a hybrid optimization technique, called hybrid particle swarm optimization and gravitational search algorithm (HPSO-GSA). Further, FDC values are also optimized such that flat passband and stopband frequency response is achieved and the absolute $$L_1$$L1-error is minimized. Finally, four design examples of 2D low-pass, high-pass, band-pass and band-stop filters are demonstrated to justify the design accuracy in terms of passband error, stopband error, maximum passband ripple, minimum stopband attenuation and execution time. Simulation results have been compared with the other optimization algorithms, such as real-coded genetic algorithm, particle swarm optimization and gravitational search algorithm. It is observed that HPSO-GSA gives improved results for 2D FIR-FDC filter design problem. In comparison with other existing techniques of 2D FIR filter design, the proposed method shows improved design accuracy and flexibility with varying values of FDCs.
TL;DR: In this paper, a frequency selective surface (FSS) with wideband frequency response in U- and V-bands is proposed, which consists of a conventional Jerusalem cross and a FAN shape on both sides of a single-layered RO4003 substrate.
Abstract: In this letter, a frequency selective surface (FSS) with wideband frequency response in U- and V-bands is proposed. This FSS consists of a conventional Jerusalem cross and a FAN shape on both sides of a single-layered RO4003 substrate. It exhibits a wide stopband of 30 GHz with attenuation more than 16 dB for the normal incidence. The unit cell is symmetrical in nature, thereby giving similar results for TE and TM operation modes. A panel of this FSS was fabricated and measured using free-space measurement to validate the simulation results. It is suitable for millimeter-wave shielding and reduction of mutual coupling in multiple-input–multiple-output (MIMO) antennas.
TL;DR: In this article, the design of multi-band bandpass filters employing stub loaded stepped-impedance resonator with defected microstrip structure (SL-SIR-DMS) is presented for the first time.
Abstract: The design of multi-band bandpass filters (BPFs) employing stub loaded stepped-impedance resonator with defected microstrip structure (SL-SIR-DMS) is presented in this study for the first time. The proposed SL-SIR-DMS is created by embedding DMS on the low-impedance line of the SL-SIR. It is found that different defected structures can lead to different frequency responses. In addition, by using DMS, tri-band and even quad-band responses can be easily achieved without increasing the resonator size. As verification, one tri-band SL-SIR-DMS and one quad-band SL-SIR-DMS are designed and analysed using even/odd-mode method. Subsequently, one tri-band BPF and one quad-band BPF have been developed with pseudo-interdigital coupling to realise good out-of-band performance. The predicted results are compared with measured ones and good agreement is achieved. Compared with BPFs using only SL-SIR, the proposed filters with DMS are more compact due to the slow-wave characteristic. Compared with the BPFs using defected ground structure to improve the stopband performance, the proposed ones can realise comparable wide stopbands but maintaining the signal integrity on the ground plane for packaging purpose.
TL;DR: In this paper, a combination of electromagnetic bandgap (EBG)-loaded half-mode substrate integrated waveguide (HMSIW) and composite right/left-handed (CRLH) HMSIW is used in this development.
Abstract: A compact bandpass filter exhibiting an ultra-wide out-of-band rejection is studied and developed. A combination of electromagnetic bandgap (EBG)-loaded half-mode substrate integrated waveguide (HMSIW) and composite right/left-handed (CRLH) HMSIW is used in this development. The proposed filter operates below the characteristic cutoff frequency of HMSIW. The CRLH HMSIW loaded with EBG structures is investigated first. The filter with a miniaturized size is then implemented with two slots etched on HMSIW to reduce coupling effects between EBG structures and interdigital capacitors. Defected microstrip structure (DMS) as feed lines are used to obtain an ultra-wide out-of-band rejection. Measured results show that this effective stopband can cover up to 10.3 times the design center frequency for a rejection level of 20 dB. The filter exhibits high selectivity, good stopband performance, and compact size.
TL;DR: In this article, a balanced bandpass filter (BPF) with mixed electric and magnetic coupling is proposed, which is implemented by using $\lambda/4$ stepped-impedance resonators (SIRs).
Abstract: In this letter, a novel balanced bandpass filter (BPF) with mixed electric and magnetic coupling is proposed, which is implemented by using $\lambda/4$ stepped-impedance resonators (SIRs). Specially, balanced coupled-line is utilized to realize the passband response in differential-mode (DM) operation and meanwhile give a wide and deep stopband in common-mode (CM) operation. Second- and third-order equivalent half-circuits are investigated and simulated, which exhibits an excellent filtering performance for DM as well as a high level suppression in CM. A prototype balanced filter operating at 5.2 GHz is realized, which has controllable transmission zeros (TZs), sharp skirts, low inserted loss and compact size for DM. Under CM excitation, the measured level of suppression of signal is over 41 dB within the passband, over 38 dB from 0 to 9 GHz and over 26 dB from 0 to 16.5 GHz.
TL;DR: In this article, the design, fabrication, and measurements of reconfigurable terahertz (THz) filters using vanadium dioxide (VO2) phase-change material (PCM), which undergoes a transition between an insulator and metal phase at 68°C (∼341 K), are reported.
Abstract: We report the design, fabrication, and measurements of reconfigurable terahertz (THz) filters using vanadium dioxide (VO2) phase-change material (PCM), which undergoes a transition between an insulator and metal phase at 68 °C (∼341 K). The filters are made of frequency selective surfaces (FSS) and heater are integrated for VO2 excitation. Two THz spatial filters are developed. A broadband on/off filter at 0.35 THz is demonstrated with 20 dB change in transmission between the on and off states. Then, a reconfigurable stopband FSS filter with tunable rejection from 0.75 to 0.55 THz is presented. The latter shows a peak with rejection of more than 90%. The two states of both filters are achieved at relatively low temperature of 68 °C, making them suitable for practical applications. Comparisons between simulation and measurement show excellent agreement for both 0.35 THz on/off filter and 0.75 to 0.55 THz tunable filters.
TL;DR: A bandpass microwave photonic filter (MPF) with ultrahigh stopband attenuation and skirt selectivity based on a simple signal cancellation technique is proposed and demonstrated.
Abstract: we propose and demonstrate a bandpass microwave photonic filter (MPF) with ultrahigh stopband attenuation and skirt selectivity based on a simple signal cancellation technique. By injecting two phase modulated signals located on opposite sides of two resonant gain peaks of a Fabry-Perot semiconductor optical amplifier (FP-SOA), two microwave frequency responses can be generated by the two input signals, respectively. The two frequency responses will add together within the passband but cancel each other out within the stopband, thus generating a MPF with simultaneous ultrahigh stopband attenuation and skirt selectivity. In the experiment the obtained MPF exhibits single passband in the range from 0 to 18 GHz and is tunable from 4 to 16 GHz by adjusting the laser wavelengths. During the tuning process the maximum stopband attenuation is 76.3 dB and the minimum 30-dB to 3-dB bandwidth shape factor is 3.5.
TL;DR: In this article, a simple and effective method to design wide-stopband bandpass filters and diplexers using uniform impedance resonators is proposed, and the design equations and design rules for both homogeneous and inhomogeneous mediums are given in detail.
Abstract: This paper proposes a simple and effective method to designing wide-stopband bandpass filters and diplexers using uniform impedance resonators. Microstrip terminated parallel coupled lines are utilized to generate the filtering functions. By adjustment of the electrical lengths of the parallel coupled lines and open-circuited stubs, multiple transmission zeros can be obtained. Appropriate positioning of these zeros enables the suppression of spurious frequencies. A complete analytic analysis is proposed to fully control the positions of transmission zeros, and the design equations and design rules for both homogeneous and inhomogeneous mediums are given in detail. Different combinations of the frequency position of the transmission zeros can provide various characteristics. To extend the stopband bandwidth, one or more transmission zeros can be distributed on different harmonic frequencies. To demonstrate the proposed method, two bandpass filters and a diplexer are designed and fabricated. The measured results are in good agreement with the simulated ones. The first filter provides a high attenuation of 40 dB up to 6.8 times the fundamental frequency $(f_{{{0}}})$ and the second filter provides a lower attenuation of 28 dB, but this time extending up to $14.9f_{{{0}}}$ .
TL;DR: This paper proposes and investigates ultra-compact, broadband tunable optical bandstop filters based on a multimode one-dimensional photonic crystal waveguide (PhCW), which provides a more compact footprint and much broader stopband than the counterparts based on microrings, long-period waveguide gratings, and multimode two-dimensional PhCWs.
Abstract: In this paper, ultra-compact, broadband tunable optical bandstop filters (OBSFs) based on a multimode one-dimensional photonic crystal waveguide (PhCW) are proposed and systematically investigated. For the wavelengths in the mini-stopband, the input mode is coupled to a contra-propagating higher order mode by the PhCW and then radiates in a taper, resulting in a stopband at the output with low backreflection at the input. Three-dimensional finite-difference time-domain method is employed to study the OBSFs. The influence of main structural parameters is analyzed, and the design is optimized to reduce the back-reflection and band sidelobes. Using localized heating, we can shift the stopband and tune the bandwidth continuously by cascading the proposed structures. Due to the strong grating strength, our device provides a more compact footprint (40 μm × 1 μm) and much broader stopband (bandwidth of up to 84 nm), compared to the counterparts based on microrings, long-period waveguide gratings, and multimode two-dimensional PhCWs.
TL;DR: In this paper, a common-mode filter (CMF) based on the silicon interposer process with through-silicon vias (TSV) is proposed to improve the electromagnetic compatibility.
Abstract: In this paper, the radiation of signaling channel that may lead to noise coupling, electromagnetic interference or radio-frequency interference problems in three-dimensional integrated circuits (3-D ICs) is discussed. To improve the electromagnetic compatibility, a common-mode filter (CMF) based on the silicon interposer process with through-silicon vias (TSV) is proposed. A differential second-order T-model circuit for transmission lines with a common inductance is proposed to characterize and design the stopband and corresponding two transmission zeros for common mode (CM). Codesigned with through-silicon vias, this TSV-based CMF (TSV-CMF) is implemented in a cost-efficient interposer process and the measurement results match well to both the equivalent circuit model and full-wave simulation. It is measured that the differential bandwidth of the TSV-CMF can reach 25 GHz and CM stopband is around 15 GHz with 20% fractional bandwidth. In addition, the suppressing frequency and bandwidth can be easily altered and improved by using more stacked chips on the interposer.
TL;DR: In this paper, a new discriminating coupling mechanism is proposed to suppress the unwanted resonance modes without affecting the desirable operating modes, which is realized by choosing suitable coupling region between the feeding lines and resonators.
Abstract: In this paper, a new discriminating coupling mechanism, which is realized by choosing suitable coupling region between the feeding lines and resonators, is proposed to suppress the unwanted resonance modes without affecting the desirable operating modes. Utilizing such a coupling mechanism, two low-temperature cofired ceramic (LTCC) bandpass filters (BPFs) are designed operating at microwave and millimeter-wave bands. One BPF realizes a wide stopband, since the third and fifth harmonics are suppressed by the discriminating coupling. The other one is an oversized 60-GHz BPF with the fundamental mode suppressed by the discriminating coupling. Due to the multilayer characteristics of the LTCC techniques, the circuit layout can be controlled flexibly to realize desirable discriminating coupling. The two filters are theoretically analyzed and implemented. Good agreement between the simulation and the measurement validates the proposed method.
TL;DR: In this article, a new hexagonal shape compact elliptical low pass filter (LPF) is introduced to improve and extend the stop band, two additional transmission zeros are created by introducing three semi-circular slots in the ground plane.
Abstract: In this work a new hexagonal shape compact elliptical low pass filter (LPF) is introduced. To improve and extend the stop band, two additional transmission zeros are created by introducing three semi-circular slots in the ground plane. Insertion loss is 18 dB in the entire pass band. Rejection band is extended up to >20 GHz with attenuation level better than −20dB. Obtained roll-off factor is 100 dB/GHz and group delay is 0.25 ns.
TL;DR: Comparative study and the simulation results reveal that the designed filter with CS gives better performance in terms of Maximum Stopband Ripple (MSR), and Stopband Attenuation (As) for low order filter design, and for higher order it also gives betterperformance in term of Maximum Pass Band Ripple (MPR).
TL;DR: In this paper, a quad-mode bandpass filter is built up based on a novel quadmode defected ground structure (DGS) resonator which has two symmetric planes, and the odd/even mode theory is applied to analyze the operating principle of the four resonances with their equivalent circuit models.
Abstract: In this letter, a quad-mode bandpass filter is built up based on a novel quad-mode defected ground structure (DGS) resonator which has two symmetric planes. The odd-/even-mode theory is applied to analyze the operating principle of the four resonances with their equivalent circuit models. The four resonances can be effectively tuned by adjusting the corresponding dimensions. The fabricated filter has a center frequency of 2.45 GHz and a wide stopband up to 7.8 GHz with a rejection below $-$ 30 dB, which extends to at least 30 GHz below $-$ 16 dB. Particularly, the filter exhibits an excellent attenuation slope of 302 dB/GHz in the upper passband transition.