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Showing papers on "Stopband published in 2006"


Journal ArticleDOI
TL;DR: A multistage design for microphotonic add-drop filters that provides reduced drop-port loss and relaxed tolerances for achieving high in-band extinction is proposed, and the first microring-resonator filters with a rectangular notch stopband in the through port are shown, with extinctions exceeding 50 dB.
Abstract: We propose and demonstrate a multistage design for microphotonic add-drop filters that provides reduced drop-port loss and relaxed tolerances for achieving high in-band extinction. As a result, the first microring-resonator filters with a rectangular notch stopband in the through port (to our knowledge) are shown, with extinctions exceeding 50 dB. Reaching 30 dB beyond previous results, without postfabrication trimming, such extinction levels open the door to microphotonic notch circuits for spectroscopy, wavelength conversion, and quantum cryptography applications. Combined with a low-loss, high-index-contrast electromagnetic design in SiN and frequency-matched microring resonators, this approach led to the first demonstration of flattop microphotonic filters meeting the stringent criteria for high-spectral-efficiency integrated add-drop multiplexers. The 40 GHz wide filters show a 20 nm free spectral range, 2 dB drop loss, and suppression of adjacent channels by over 30 dB.

203 citations


Journal ArticleDOI
TL;DR: In this paper, a compact double equilateral U-shaped defected ground structure (DGS) unit is proposed, which provides dual finite attenuation poles that can be independently controlled by the DGS lengths.
Abstract: A compact double equilateral U-shaped defected ground structure (DGS) unit is proposed. In contrast to a single finite attenuation pole characteristic offered by the conventional dumbbell DGS, the proposed DGS unit provides dual finite attenuation poles that can be independently controlled by the DGS lengths. A 2.4-GHz microstrip lowpass filter using five cascaded double U-shaped DGS units is designed and compared with conventional DGS lowpass filters. This low pass filter achieves a wide stopband with overall 30-dB attenuation up-to10 GHz and more than 42% size diminution.

179 citations


Journal ArticleDOI
TL;DR: In this paper, a tunable left-handed transmission line, based on split-ring resonators, was designed and fabricated with tuning ranges as wide as 30% and negative effective permeability provided by the VLSRRs in a narrow band above their resonant frequency.
Abstract: In this paper, it is demonstrated that varactor-loaded split-ring resonators (VLSRRs) coupled to microstrip lines can lead to metamaterial transmission lines with tuning capability. Both negative permeability (mu<0) and double (or left-handed) negative media have been designed and fabricated with tuning ranges as wide as 30%. The negative effective permeability is provided by the VLSRRs in a narrow band above their resonant frequency, which can be bias controlled by virtue of the presence of diode varactors. To achieve a negative effective permittivity in the left-handed structure, metallic vias emulating shunt inductances are periodically placed between the conductor strip and the ground plane. The lumped-element equivalent-circuit models of the designed structures have been derived. It has been found that these models provide a good qualitative description of device performance. Since the VLSRR microstrip line and the line loaded with both VLSRRs and vias exhibit stopband and bandpass behavior, respectively, the ideas presented in this study can be applied to the design of narrowband tunable frequency-selective structures with compact dimensions. This is the first time that a tunable left-handed transmission line, based on SRRs, is proposed

170 citations


Journal ArticleDOI
TL;DR: In this article, a wide-stopband and compact microstrip bandpass filters (BPFs) are proposed using various dissimilar quarter-wavelength stepped-impedance resonators (SIRs) for multiple spurious suppression.
Abstract: 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.

162 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed a microbeam device which couples the inherent benefits of a resonator with purely-parametric excitation with the simple geometry of a microbeam.
Abstract: Electrostatically-actuated resonant microbeam devices have garnered significant attention due to their geometric simplicity and broad applicability. Recently, some of this focus has turned to comb-driven microresonators with purely-parametric excitation, as such systems not only exhibit the inherent benefits of MEMS devices, but also a general improvement in sensitivity, stopband attenuation and noise rejection. This work attempts to combine each of these areas by proposing a microbeam device which couples the inherent benefits of a resonator with purely-parametric excitation with the simple geometry of a microbeam. Theoretical analysis reveals that the proposed device exhibits desirable response characteristics, but also quite complex dynamics. Of particular note is the fact that the device's nonlinear frequency response is found to be qualitatively dependent on the system's ac excitation amplitude. While this flexibility can be desirable in certain contexts, it introduces additional design and operating limitations. While the principal focus of this work is the proposed system's nonlinear response, the work also contains details pertaining to model development and device design.

162 citations


Journal ArticleDOI
TL;DR: In this paper, the topologies of one-dimensional peri- odic unit cells are designed for target frequency band struc- tures characterizing longitudinal wave motion, and binary and mixed formulations are developed for the treatment of the optimization problems.
Abstract: An important dispersion-related characteristic of wave propagation through periodic materials is the existence of frequency bands. A medium effectively attenuates all inci- dent waves within stopbands and allows propagation within passbands. The widths and locations of these bands in the frequency domain depend on the layout of contrasting mate- rials and the ratio of their properties. Using a multiobjective genetic algorithm, the topologies of one-dimensional peri- odic unit cells are designed for target frequency band struc- tures characterizing longitudinal wave motion. The decision variables are the number of layers in the unit cell and the thickness of each layer. Binary and mixed formulations are developed for the treatment of the optimization problems. Designs are generated for the following novel objectives: (1) maximum attenuation of time harmonic waves, (2) maximum isolation of general broadband pulses, and (3) filtering sig- nals at predetermined frequency windows. The saturation of performance with the number of unit-cell layers is shown for the first two cases. In the filtering application, the trade-off between the simultaneous realization of passband and stop- band targets is analyzed. It is shown that it is more difficult to design for passbands than it is to design for stopbands. The design approach presented has potential use in the de- velopment of vibration and shock isolation structures, sound isolation pads/partitions, and multiple band frequency filters, among other applications.

157 citations


Journal ArticleDOI
TL;DR: In this article, a common office partition wall was transformed into a frequency-selective (FS) wall by attaching a custom-designed band-stop frequency selective surface (FSS) as a cover on the wall surface.
Abstract: Modifying the indoor wireless physical propagation environment to reduce the interference level was investigated and demonstrated in this research. A common office partition wall (that was in the main propagation path) was transformed into a frequency-selective (FS) wall by attaching a custom-designed band-stop frequency-selective surface (FSS) as a cover on the wall surface. In-situ measurements showed that this frequency-selective wall filtered out signals operating at 5.4-6.0 GHz (IEEE 802.11a) by an additional attenuation of 10-15 dB compared to the unmodified wall, for incident angles ranging from 0deg-55deg in the azimuth plane and 0deg-20deg in the elevation plane. An attenuation of 10-15 dB in signal strength in the stop band is considered to be significant and beneficial in interference reduction, whereas in the pass-band region (such as 1.8 GHz for cellular telephones), signals experienced only marginally more attenuation than that through the unmodified wall. Results also suggest that the interactions between the FSS and the wall surface can be minimized with an appropriate FSS design, which leads to a feasible and practical product solution: frequency-selective wallpapers. In addition, installation issues, such as misalignment of FSS sheets on the wall, were also examined

156 citations


Journal ArticleDOI
TL;DR: In this article, a ring resonator with two different geometric dimensions is derived and designed to have identical fundamental and the first higher-order resonant frequencies, and the proposed filter has smaller size as compared with the basic topology of stopband filters and stepped-impedance-resonator (SIR) filters.
Abstract: In this letter, a novel compact ring dual-mode with adjustable second-passband for dual-band applications are presented. A ring resonator with two different geometric dimensions are derived and designed to have identical fundamental and the first higher-order resonant frequencies, and to establish appropriate couplings in the structure. Moreover, the proposed filter has smaller size as compared with the basic topology of stopband filters and stepped-impedance-resonator (SIR) filters. The measured filter performance is in good agreement with the simulated response.

129 citations


Journal ArticleDOI
TL;DR: In this paper, the first experimental demonstration of 2D broadband reflectors is presented, which is based on the coupling of free space waves with two slow Bloch modes of the crystal.
Abstract: Two-dimensional (2-D) compact photonic crystal reflectors on suspended InP membranes were studied under normal incidence. We report the first experimental demonstration of 2-D broadband reflectors (experimental stopband superior to 200 nm, theoretical stopband of 350 nm). They are based on the coupling of free space waves with two slow Bloch modes of the crystal. Moreover, they present a very strong sensitivity of the polarization dependence, when modifying their geometry. A compact (50/spl times/50 /spl mu/m/sup 2/) demonstrator was realized and characterized, behaving either as a broadband reflector or as a broadband transmitter, depending on the polarization of the incident wave. Experimental results are in good agreement with numerical simulations.

110 citations


Journal ArticleDOI
TL;DR: In this paper, a defected ground structure (DGS) consisting of concentric circular rings in different configurations is experimentally studied to examine the stopband characteristics, and a metallic shielding is introduced at the back of the DGS to suppress any leakage or radiation.
Abstract: A new defected ground structure (DGS) consisting of concentric circular rings in different configurations is experimentally studied to examine the stopband characteristics. Unlike previous DGS designs, a metallic shielding is introduced at the back of the DGS to suppress any leakage or radiation, and this would be advantageous for microwave circuit applications. A wide stopband is demonstrated with a set of prototypes designed for X-band. Its application to suppressing mutual coupling in microstrip patch arrays is demonstrated

110 citations


Journal ArticleDOI
TL;DR: In this article, a cross-shape defected ground structure (CSDGS) was proposed for low-pass filter with an ultra-wide stopband, which not only supports conventional DGS performances with a sharp rejection, but also exhibits an ultra wide stopband.
Abstract: This letter presents a novel low-pass filter with an ultra-wide stopband. The proposed filter is comprised of a new cross-shape defected ground structure (CSDGS). By using this structure, the filter not only supports conventional DGS performances with a sharp rejection, but also exhibits an ultra-wide stopband. For the deigned low-pass filter, an insertion loss of less than 2dB from dc to 3.5GHz and the rejection is better than 20dB from 4.3 to 15.8GHz. Predicted performances show widened and deepened stopband beyond the low passband. Furthermore, it is confirmed by measurement.

Journal ArticleDOI
TL;DR: In this article, complementary split ring resonators are used to design a compact, low insertion loss (IL), low pass filter with sharp cut-off, and a prototype filter implementing area is 0.23 lambdagtimes0.09 lambda g, Lambdag being the guided wavelength at 3-dB cutoff frequency (fc) 1.887GHz.
Abstract: Complementary split ring resonators are used to design compact, low insertion loss (IL), low pass filter with sharp cut-off. A prototype filter implementing area is 0.23 lambdagtimes0.09lambda g, lambdag being the guided wavelength at 3-dB cut-off frequency (fc) 1.887GHz. Maximum IL is within 0.5dB up to 1.717GHz and 20-dB stopband extends up to 3.4fc

Journal ArticleDOI
TL;DR: In this article, a switchable bandpass filter with a wide stopband rejection was proposed, where the loaded diodes were used to switch the resonance conditions of the stepped-impedance resonators.
Abstract: Stepped-impedance resonators with diodes loaded at one end are used to develop switchable bandpass filters in this paper. The loaded diodes are used to switch the resonance conditions of the stepped-impedance resonators. The equations for resonance conditions of the stepped-impedance resonators with different loads at one end are derived and discussed. With these derived equations, the switchable filters can be easily designed and synthesized using the coupled-resonator filter theory. When the switchable filter is switched on, a bandpass filter response with a wide stopband rejection is achieved by making the on-state coupled resonators have the same fundamental resonant frequency, but different higher order resonant frequencies. When switched off, a high and wideband isolation is obtained by properly misaligning the resonant modes of the off-state resonators. The design concept is demonstrated by two single-pole-single-throw fourth-order Butterworth-type switchable microstrip bandpass filters, which utilize two and three switched stepped-impedance resonators, respectively. Finally, a compact single-pole-double-throw switchable microstrip bandpass filter using common resonators is demonstrated for wireless communication applications

Journal ArticleDOI
TL;DR: In this article, a periodic stepped-impedance ring resonator (PSIRR) is proposed to design dual-mode bandpass filters with a miniaturized area and desirable upper stopband characteristics.
Abstract: 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.

Journal ArticleDOI
TL;DR: This work describes a 16-channel critical-like spaced, high stopband attenuation, micropower, and small integrated circuit (IC) area finite impulse response filter bank core for power-critical hearing aids and shows that the design is very competitive compared to reported designs, and with the advantages of higher stop band attenuation and linear phase frequency response.
Abstract: We describe a 16-channel critical-like spaced, high stopband attenuation (ges60 dB, 109thtimes16-order), micropower (247.5 muW@1.1 V, 0.96 MHz), small integrated circuit (IC) area (1.62 mm2@0.35-mum CMOS) finite impulse response filter bank core for power-critical hearing aids. We achieve the low-power and small IC area attributes by our proposed common pre-computational unit to generate a set of pre-calculated intermediate values that is shared by all 16 channels. We also take advantage of the consecutive zeros in the coefficients of the filter channels, allowing the multiplexers therein to be simplified. We show that our design is very competitive compared to reported designs, and with the advantages of higher stopband attenuation and linear phase frequency response. Compared to a design using the usual approach, our design features 47% lower power dissipation and 37% smaller IC area

Journal ArticleDOI
TL;DR: In this article, three types of novel microstrip bandpass filters, a square split ring stepped-impedance bandpass filter (SRSRSBFF), a square ring SRLB filter, and a dual-mode square ring RSB filter are proposed.
Abstract: Three types of novel microstrip bandpass filters, a square split ring stepped-impedance bandpass filter, a square ring stepped-impedance bandpass filter, and a dual-mode square ring bandpass filter, which operate from L to S waveband are proposed, their filter performances are calculated. In these novel structures, ring stepped-impedance resonator, DGS and dual-mode technique are applied to not only reduce the volume but also improve the frequency responses of filters. The optimized results show that microstrip bandpass filter with DGS has nicer performances such as low insertion losses, wide stopband responses etc., while with dual-mode technique, a pair of transmission zeros can be implemented and the filter performances are effectively improved. The filters proposed in this paper have outstanding advantages such as compact and novel structures, small volumes, high selectivity, wide stopband responses, low insertion losses and so on, and can be applied in wearable systems.

Patent
20 Oct 2006
TL;DR: In this article, a hybrid electromagnetic bandgap (EBG) structure for broadband suppression of noise on printed wiring boards includes an array of coplanar patches interconnected into a grid by series inductances, and a corresponding array of shunt LC networks connecting the coplanars patches to a second conductive plane.
Abstract: A hybrid electromagnetic bandgap (EBG) structure for broadband suppression of noise on printed wiring boards includes an array of coplanar patches interconnected into a grid by series inductances, and a corresponding array of shunt LC networks connecting the coplanar patches to a second conductive plane. This combination of series inductances and shunt resonant vias lowers the cutoff frequency for the fundamental stopband. The series inductances and shunt capacitances may be implemented using surface mount component technology, or printed traces. Patches may also be interconnected by coplanar coupled transmission lines. The even and odd mode impedances of the coupled lines may be increased by forming slots in the second conductive plane disposed opposite to the transmission line, lowering the cutoff frequency and increasing the bandwidth of the fundamental stopband. Coplanar EBG structures may be integrated into power distribution networks of printed wiring boards for broadband suppression of electromagnetic noise.

Journal ArticleDOI
TL;DR: In this paper, a design of multiple-stopband filters is presented for the suppression of interfering signals in UWB applications, since possible interferers can be located at fixed frequencies or within a defined frequency band.
Abstract: A design of multiple-stopband filters is presented for the suppression of interfering signals in UWB applications. Since possible interferers can be located at fixed frequencies or within a defined frequency band, the design of both fixed and tunable narrow stopband filter sections is addressed. For multiple fixed stopband filters, bent resonators, coupled to the main line, are introduced in order to more effectively suppress harmonics. A new tunable tapped stopband section is proposed, which allows the simultaneous control of stopband frequency and bandwidth. The final multiple-stopband design combines fixed and tunable sections and simultaneously suppresses interferences from global system for mobile communication, wireless local area network, worldwide interoperability for microwave access, and industrial-scientific-medical applications. Measurements verify the design process

Journal ArticleDOI
TL;DR: Huang et al. as mentioned in this paper proposed a mechanism similar to the drum-like silencer with tensioned membranes, however, the logarithmic bandwidth over which the reflection occurs is much wider than that of a drum-based silencer of the same cavity geometry, the typical difference being nearly one octave band.
Abstract: When a segment of a rigid duct is replaced by a plate backed by a hard-walled cavity, grazing incident sound waves induce plate bending, hence sound reflection. The mechanism is similar to the drumlike silencer with tensioned membranes [L. Huang, J. Acoust. Soc. Am. 112, 2014–2025 (2002)]. However, the logarithmic bandwidth over which the reflection occurs is much wider than that of a drumlike silencer of the same cavity geometry, the typical difference being nearly one octave band. The difference in the silencing performance is explained in terms of the intermodal acoustic interference between the odd and even in vacuo vibration modes. For a given cavity volume, the widest stopband for noise in air is obtained by using long plates with two free lateral edges parallel with the duct axis. The optimal material should be stiff and light, and the critical parameter is found to be the ratio of the Young’s modulus over the cube of density. Typically, this ratio is 250 times higher than those of common metallic ...

Journal ArticleDOI
TL;DR: In this article, a low-temperature-coeded ceramic (LTCC) bandpass filter with high stopband rejection is presented for multistandard coexisted wireless communication applications, such as the integrated wireless local area network (WLAN)/wavelength code-division multiple access handset, the dual-band triplemode WLANs, and the global system for mobile communications/global positioning system receivers.
Abstract: A low-temperature-cofired ceramic (LTCC) bandpass filter with high stopband rejection is presented for multistandard coexisted wireless communication applications, such as the integrated wireless local area network (WLAN)/wavelength code-division multiple access handset, the dual-band triple-mode WLANs, and the global system for mobile communications/global positioning system receivers. By improving the filter cell structure, 2n transmission zeros can be generated to achieve wide-band suppression from cascading n filter cells. The presented method provides the design flexibility of locating these transmission zeros distributed in the lower and upper stopbands. An LTCC bandpass filter with four transmission zeros has been implemented for experimental demonstration. The measured insertion loss is less than 1.5 dB at 2500 MHz, and four transmission zeros are obtained at 1.64, 1.88, 4.36, and 5.32 GHz, respectively. These result in 48-59 dB for lower stopband suppression and 38-55 dB for higher stopband reduction. This paper demonstrates that the proposed filter is extremely suitable for the multiband RF transceivers where the cross-band interference must be adequately reduced.

Journal ArticleDOI
TL;DR: In this article, two π-phase shifts are introduced in a uniform fiber Bragg grating structure and a dual-transmission band opens in the stopband of FBG.
Abstract: Two π-phase shifts are introduced in a uniform fiber Bragg grating (FBG) structure and a dual-transmission-band opens in the stopband of FBG When incorporating this kind of FBG filter in a fiber ring cavity with a semiconductor optical amplifier (SOA) acted as gain medium, a stable dual-wavelength lasing with wavelength spacing of 0032, 0052 and 0068 nm is achieved, respectively Therefore, the laser output is heterodyned on a photodetector and desired microwave frequencies of 315, 616 and 808 GHz are generated

Journal ArticleDOI
TL;DR: In this paper, a new class of frequency-selective surfaces (FSSs), to be used as quasi-optical filters for harmonic suppression in submillimeter-wave frequency multipliers, is proposed and experimentally verified.
Abstract: A new class of frequency-selective surfaces (FSSs), to be used as quasi-optical filters for harmonic suppression in submillimeter-wave frequency multipliers, is proposed and experimentally verified. The FSSs consist of two-dimensional aperture arrays and are made from microstructured aluminum on electrically thick, high-resistivity silicon substrates. This leads to a very good mechanical stability, reasonably low insertion loss, and permits manufacture of the structure by using standard processes available from the semiconductor industries. This paper presents the design, fabrication, and testing of two sets of prototypes, the former with a passband at 300 GHz and a stopband at 450 GHz and the latter with a passband at 600 GHz and a stopband at 750 GHz. For both frequency ranges, FSSs with rectangular slots and with dogbone-shaped holes have been designed by using the method of moments/boundary integral-resonant mode expansion method. The effect of ohmic and dielectric losses has been determined by using the commercial code HFSS. Several prototypes have been fabricated, and measured by terahertz time-domain spectroscopy and continuous wave measurements, showing high reproducibility of the machining process, insertion loss between 1.0 and 1.6 dB, and stopband attenuation larger than 30 dB. Finally, we demonstrate that the incidence angle can be used as a degree of freedom for fine tuning the stopband, without practically changing the frequency response in the passband

Journal ArticleDOI
30 Oct 2006
TL;DR: In this article, the authors proposed a bandstop filter with high skirt selectivity and wide rejection bandwidth by means of open-ended lambda g/4 stepped-impedance resonators (SIRs) and spur line sections.
Abstract: Bandstop filters (BSFs) with high skirt selectivity as well as wide rejection bandwidth are designed by means of open-ended lambda g /4 stepped-impedance resonators (SIRs) and spur-line sections. Base on the formula of an SIR, the frequency of a transmission zero (f z ) is accurately predicted. It is found that the impedance and length ratio can be simultaneously obtained to improve stopband performance of the filters. The transmission zero is purposely located at a lower frequency to achieve the high skirt selectivity. On the contrary, if it is adequately situated at a higher frequency, the stopband bandwidth can be increased. Also, the spur-line structure is investigated by transmission line theory and applied to provide an extra transmission zero in the stopband. With a proper choice of the even- and odd-mode characteristic impedances of the spur-line, the stopband bandwidth can be further extended. Realised by planar microstrip technology, the proposed BSF with its high skirt selectivity has a maximal value of 86.8 dB/GHz, while the other type of BSF can further widen the -20 dB stopband by 29% significantly, when incorporating the spur-line into the BSF with an SIR. Both have a size reduction benefit of better than 40% with respective to the conventional case

Journal ArticleDOI
TL;DR: In this paper, a photonic crystal power/ground layer (PCPL) is proposed to suppress the power and ground bounce noise (P/GBN) or simultaneously switching noise (SSN) in high-speed digital circuits.
Abstract: A novel photonic crystal power/ground layer (PCPL) is proposed to efficiently suppress the power/ground bounce noise (P/GBN) or simultaneously switching noise (SSN) in high-speed digital circuits. The PCPL is designed by periodically embedding high dielectric-constant rods into the substrate between the power and ground planes with a small area filling ratio less than 10%. The PCPL can efficiently eliminate the SSN (over 60 dB) with broad stopband bandwidth (totally over 4 GHz) below the 10-GHz range, and in the time domain, the P/GBN can be significantly reduced over 90%. The PCPL not only performs good power integrity, but also keeps good signal quality with significant improvement on eye patterns for high-speed signals with via transitions. In addition, the proposed designs perform low radiation (or electromagnetic interference) caused by the SSN within the stopbands. These extinctive behaviors both in signal integrity and electromagnetic compatibility are demonstrated numerically and experimentally. Good agreements are seen. The bandgap maps to help design the PCPL structure are also demonstrated based on the two-dimensional finite-difference time-domain method

Journal ArticleDOI
TL;DR: In this article, the authors proposed a planar bandpass filter design with wide stopband and double split-end quarter-wave-length /spl lambda/4 resonator to reduce the resonator size while providing additional transmission zeros.
Abstract: 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.

Journal ArticleDOI
TL;DR: In this paper, a second-and fourth-order microstrip bandpass filters are proposed based on the folded quarter-wavelength resonators, which are mainly coupled through the shunt inductors connected to the ground.
Abstract: Compact microstrip bandpass filters (second- and fourth-order) are proposed based on the folded quarter-wavelength (/spl lambda//4) resonators, which are mainly coupled through the shunt inductors connected to the ground. By introducing a cross-coupling capacitance directly between the input and output ports of the second-order filter, a pair of transmission zeros may be created to improve the selectivity. Moreover, by an extension of the proposed second-order filter with the incorporation of an additional cross-coupling capacitance, a fourth-order filter is also proposed in which two pairs of transmission zeros may be created to improve both the selectivity and stopband rejection. The proposed fourth-order filter also has the merits of small circuit area and no spurious response up to 3f/sub 0/, where f/sub 0/ is the passband center frequency. To provide effective design tools, simple equivalent-circuit models are also established.

Journal ArticleDOI
TL;DR: In this paper, a compact structure with three controllable finite attenuation poles at stopband is presented, composed of a pair of symmetrical parallel coupled-lines and a capacitive load.
Abstract: A novel compact structure with three controllable finite attenuation poles at stopband is presented. The new structure is composed of a pair of symmetrical parallel coupled-lines and a capacitive load. With this configuration, three finite attenuation poles are available, which can improve the stopband characteristics of low-pass filters (LPFs) or the upper stopband performances of band-pass filters. The research method is based on a transmission-line model for tuning the finite attenuation poles. In order to examine the feasibility of the proposed structure, a new type of LPF with broad stopband and sharp cutoff frequency response is designed, fabricated, and measured. The experimental results of the fabricated circuit agree well with the simulation and analytical ones

Patent
09 Jan 2006
TL;DR: In this paper, a fabrication method of group III nitride-based distributed Bragg reflectors for VCSELs was proposed, which suppresses the generation of cracks and provides high reflectivity, broad stopband, and adaptability to optical devices such as vertical cavity surface emitting lasers, micro-cavity light emitting diodes, resonance cavity light emitting diode and photodetectors.
Abstract: To solve the existing problems in distributed Bragg reflectors (DBR) used in the prior art, the present invention provides a fabrication method of group III nitride based distributed Bragg reflectors (DBR) for vertical cavity surface emitting lasers (VCSELs), which suppresses the generation of cracks, and a distributed Bragg reflector with high reflectivity, broad stopband, and adaptability to optical devices such as vertical cavity surface emitting lasers, micro-cavity light emitting diodes, resonance cavity light emitting diodes and photodetectors.

Journal ArticleDOI
TL;DR: A new approach to beam-space preprocessing with an improved robustness against out-of-sector interfering sources is developed, and Computationally efficient convex formulations for these beam- space matrix filter design problems are derived using second-order cone (SOC) programming.
Abstract: Beam-space data preprocessing is a powerful tool commonly used in array processing to reduce the computational burden and improve the performance of high-resolution direction-finding algorithms. However, currently used beam-space techniques appear to lack robustness in the presence of sources that are located outside the beam-space angular sectors-of-interest. In this paper, a new approach to beam-space preprocessing with an improved robustness against such out-of-sector interfering sources is developed. Our techniques design the beam-space matrix filter based on proper tradeoffs between the in-sector (passband) source distortion and out-of-sector (stopband) source attenuation. Computationally efficient convex formulations for these beam-space matrix filter design problems are derived using second-order cone (SOC) programming.

Journal ArticleDOI
TL;DR: In this article, a waveguide design is proposed to provide phase matching for nonlinear optical processes by designing the structure to guide the fundamental frequency by total internal reflection and the second harmonic (SH) frequency by transverse Bragg reflection.
Abstract: In this paper, we introduce and analyze a novel wave-guide design to provide phase matching for nonlinear optical processes. Phase matching is achieved by designing the structure to guide the fundamental frequency by total internal reflection and the second harmonic (SH) frequency by transverse Bragg reflection. By forcing the SH mode to operate in the middle of the Bragg stopband, we solve for the waveguide dimensions for arbitrary waveguide materials, given the material dispersion between the fundamental and SH frequencies. Using GaAs-AlGaAs as an example, we analytically investigate and quantify properties such as nonlinear coupling efficiency, bandwidth, tunability, and limitations due to dispersion. The technique shows tremendous promise when compared to alternate technologies, where it is particularly attractive as an effective means to obtain ultralow-loss nonlinear optical elements for monolithic integration with coherent light sources and other active devices.