Showing papers by "Wen-Yan Yin published in 2013"

Matrix Exponential FDTD Modeling of Magnetized Graphene Sheet

Abstract: A novel finite-difference time-domain (FDTD) method is developed for modeling two-dimensional graphene sheet biased with a magnetostatic field. With the use of Dirac Delta function, the graphene sheet is modeled as a polarization current source characterized by an auxiliary equation (AE). Laplace transform and matrix exponential (ME) technique are applied to derive the time-domain mathematical formulations. Numerical experiments are carried out to verify the proposed method in comparison with the analytical results.

Substrate-Integrated Waveguide Bandpass Filters With Planar Resonators for System-on-Package

Abstract: This paper proposes some novel substrate-integrated waveguide (SIW) bandpass filters combined with planar resonators. According to specific topologies, microstrip lines with different electrical lengths are introduced into their designs. Their corresponding phase-shift characteristics are used to obtain the desired couplings between SIW cavities and the microstrip resonator. Two third-order filter samples are realized. One has a single transmission zero below the passband and the other possesses a quasi-elliptic response. Further, a fourth-order filter is developed by effectively superpositing two individual third-order topologies. It shows better frequency selectivity and flat in-band group delay, with good agreement between the measured and the simulated S-parameters. Their compactness and high rejection in the stopbands make them very suitable for system-on-package.

Collaborative Design of a New Dual-Bandpass 180 $^{\circ}$ Hybrid Coupler

Abstract: A new dual-bandpass 180° hybrid coupler, based on four properly designed shorted-stub loaded stepped-impedance resonators, is proposed in this paper. In order to construct the collaboratively designed coupler/filter, the resonators are coupled magnetically and electrically with each other through three shorted stubs and an open coupled line, respectively. According to the approach of filter synthesis and the derived design equations, the characteristic admittances and electrical lengths of the resonators and coupling sections are determined to achieve the desired resonant frequencies, external Q factors, and internal coupling coefficients for dual passbands. A design procedure is provided. The design flexibilities for ratios of central frequencies and achievable bandwidths are explored. The component shows both filtering and power dividing functions within two specific passbands, whose good performances are demonstrated by the simulated and measured results. The two second-order passbands of a fabricated prototype are located at 2.42 and 5.84 GHz, with 4.6% and 5.2% bandwidths, respectively. The insertion losses are 1.0 and 1.4 dB over 3-dB power division. The isolations are better than 23.5 and 32.8 dB. In both the in-phase and out-of-phase responses, the in-band amplitude and phase imbalances are always within -1.6-0.6 dB and -6.5°-9.5°, respectively.

A Novel Compact Dual-Band Antenna Array With High Isolations Realized Using the Neutralization Technique

Abstract: A novel compact dual-band antenna array with high isolations is presented in this paper. It consists of four antenna elements with two feeding networks, and it operates at dual-band of 0.89–0.96 and 1.7–2.2 GHz with return loss more than 9 dB, respectively. Two feeding networks are made of a wideband balun and a Wilkinson power divider, respectively. The two-port symmetrical array is constructed using the neutralization technique (NT), leading to the array port isolation over 30 dB from 0.5 to 3.0 GHz. Such a compact dual-band antenna array is realized and its gains and normalized patterns for both ports ${\rm P}_{1}$ and ${\rm P}_{2}$ are measured, with good agreements obtained in comparison with the simulated ones.

Dielectric Resonators With High $Q$ -Factor for Tunable Low Phase Noise Oscillators

Abstract: This paper demonstrates the realization of tunable microwave low phase noise oscillators. A ceramic-based dielectric resonator enclosed in a metallic cavity with an unloaded Q of 13000 is proposed. The relationship between geometric parameters and resonant frequency is determined. The dielectric puck is then incorporated into multilayer printed circuit boards by using substrate-integrated waveguide techniques. The results show that the resonator resonates at TE01δ mode with a frequency of 13.3 GHz. Therefore, 13.3 GHz dielectric resonator oscillators with both mechanic and electronic tuning are built. The oscillator includes a pseudomorphic high-electron-mobility transistor low-noise amplifier and an electronic phase shifter. The measured phase noise of the oscillator is -121.7 dBc/Hz at a 10-kHz offset. The calculated and measured phase noise results show a difference of 3 dB.

Development of a Novel FDTD (2, 4)-Compatible Conformal Scheme for Electromagnetic Computations of Complex Curved PEC Objects

Abstract: We present a modified fourth-order finite-difference time-domain [FDTD (2, 4)] conformal scheme for accurately computing electromagnetic characteristics of some complex three-dimensional (3D) perfectly conducting (PEC) objects. It has higher accuracy and efficiency than those of conventional FDTD and FDTD (2, 4) methods, as coarse meshes are employed with staircase errors reduced effectively during its implementation. Two integration loops of the Faraday's law are used for updating magnetic field components, while the updating equations of electric field ones are the same as those in the normal FDTD method. A rigorous analysis of its global stability, based on the conventional high-order FDTD stability criterion and the Fourier method, is also performed. In order to obtain stable and accurate numerical results, a user-defined geometric precision technique, which gives a criterion for determining the time step, is employed for our computations. It is numerically demonstrated that using our proposed FDTD (2, 4)-compatible conformal scheme, high accuracy and low dispersion errors can be achieved for fast predicting radar cross sections as well as induced current distribution of some complex 3-D structures.

One-step leapfrog ADI-FDTD method for simulating electromagnetic wave propagation in general dispersive media.

Abstract: The one-step leapfrog alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method is reformulated for simulating general electrically dispersive media. It models material dispersive properties with equivalent polarization currents. These currents are then solved with the auxiliary differential equation (ADE) and then incorporated into the one-step leapfrog ADI-FDTD method. The final equations are presented in the form similar to that of the conventional FDTD method but with second-order perturbation. The adapted method is then applied to characterize (a) electromagnetic wave propagation in a rectangular waveguide loaded with a magnetized plasma slab, (b) transmission coefficient of a plane wave normally incident on a monolayer graphene sheet biased by a magnetostatic field, and (c) surface plasmon polaritons (SPPs) propagation along a monolayer graphene sheet biased by an electrostatic field. The numerical results verify the stability, accuracy and computational efficiency of the proposed one-step leapfrog ADI-FDTD algorithm in comparison with analytical results and the results obtained with the other methods.

Experimental Investigation and Analysis of the LDMOS FET Breakdown Under HPM Pulses

Abstract: In this paper, thermal breakdown effects in a laterally diffused MOS (LDMOS) FET under the impact of high-power microwave (HPM) pulses are investigated by theoretically analyzing, modeling, and measuring. Experimental investigations of the LDMOS FET-based power amplifier (PA) are performed under different pulse durations. The measurement system consists of an adjustable HPM source, one controller, couplers, limiters, attenuators, one four-channel oscilloscope, and a DUT. By increasing the input pulse power level, electrothermal breakdown is observed. The breakdown temperature is calculated by using a 2-D analytic model based on the measured power to failure data. Then, our developed time-domain finite-element numerical algorithm is used to characterize temperature distribution and transient performance of the LDMOS FET. The energy capability, which defines the maximum energy that the device can handle, is 15.5 mJ under the pulse duration of 1 ms with a breakdown temperature of 605 K.

Efficient Evaluation of Double Surface Integrals in Time-Domain Integral Equation Formulations

Abstract: A new integration approach is presented for accurately calculating time-domain EFIE, MFIE, and CFIE matrix elements over triangular domains. It mainly consists of a radial integration scheme for handling weakly singular and near-hypersingular inner integrals and some new smoothing techniques for treating outer two-dimensional (2-D) integrals. The proposed approach has sufficient generality and efficiency for solving time-domain integral equations (TDIE) with arbitrary types of temporal basis functions and temporal discretization schemes, such as marching-on-in-time (MOT), marching-on-in-degree (MOD), and finite difference delay modeling/convolution quadrature (FDDM/CQ), etc. The numerical results for calculating some typical integrals are given to demonstrate its capability, with high accuracy and rapid convergence rate achieved.

Design of a Miniaturized Dual-Band Double-Folded Substrate Integrated Waveguide Bandpass Filter with Controllable Bandwidths

Abstract: One miniaturized multilayer dual-band bandpass fllter (BPF) is developed using standard low temperature co-flred ceramic (LTCC) technology. The fllter makes use of four double-folded substrate integrated waveguide (SIW) resonators. Two sets of coupling paths between the source and load are implemented to generate dual- band responses. Utilizing this method, the two passbands can operate at independent frequencies and the bandwidth can be easily controlled. High isolation is obtained between two passbands, and two pairs of transmission zeros close to the passband edges are generated by source- load coupling, resulting in high skirt-selectivity. Good agreement between the simulated and measured results of the fllter sample is obtained, with its high electrical performance validated.

Compact Tunable Bandpass Filter With a Fixed Out-of-Band Rejection Based on Hilbert Fractals

Abstract: This paper proposes a new type of compact tunable bandpass filter with bandwidth tuning and out-of-band fixed rejection. Because we employ the modified Hilbert fractal structure loaded with varactors as resonators, the tunable filter has a very compact configuration and a constant shape over the entire tuning range. The frequency selectivity is improved by introducing a cross coupling between the source and the load. As a result of the utilization of a pair of properly designed feedlines, the frequency tuning and the out-of-band rejection of the filter are independent of each other, which simplifies its operation significantly. Two filter prototypes have been realized with the same size of 25.0 × 17.0 × 1.0 mm3. Their superior performances have been demonstrated experimentally, with good agreement obtained between their simulated and measured S-parameters.

Modeling and Characterization of On-Chip Interconnects

Abstract: In this article, one distributed circuit model for the on-chip single interconnect will be introduced at first, where all the lumped elements are frequency independent and can be directly obtained from its geometrical and physical parameters. This ensures proper scalability of the model parameters because no optimization tuning or fitting for them is involved. Some popular and low-cost techniques, such as patterned ground shield (PGS) structures for suppressing the substrate loss of silicon substrate at high frequencies and differential signal transmission, are also addressed here. Then, electromagnetic modeling of on-chip coupled (a)symmetrical interconnects will be performed, including all distributed parameters. The average power handling capability (APHC) of on-chip interconnects and even thin-film microstrip lines (TFML) are also addressed here. Finally, the electrothermal analysis of multilevel interconnects under electrostatic discharge (ESD) stress will be reported using the time-domain finite-element method (FEM). Keywords: on-chip interconnect; modeling

On the Source Implementation for the Leapfrog ADI-FDTD Method

Abstract: Different source implementations for the leapfrog ADI-FDTD method including both current and hard sources are investigated in this letter. It is shown that, different from the conventional ADI-FDTD method, the leapfrog one always possesses asymmetry errors, while the hard source results in larger asymmetry errors than the current source. An optimal current source derived from the conventional ADI-FDTD method is then presented. In addition, it is found that the hard source is less accurate than the current source as the CFL number increases.

A triple-mode ring dielectric resonator band-pass filter using substrate integrated waveguide (SIW)

Abstract: This paper presents a design of triple mode ring dielectric resonator band-pass filter. The first mode TM010 and the second degenerated modes TM110 were excited. Instead of using conventional metal enclosures, substrate integrated waveguide (SIW) was used for easily integrating with other microwave circuits. Analytic equations were derived to determine the resonant frequencies and the quality factor of the ring dielectric resonator filter. It has been found that the calculated results agreed with simulated ones by using EM software. To develop a triple mode ring dielectric resonator filter, novel input and output structures were realized. The measured insertion of the filter is about 0.6dB with 3-dB fractional bandwidth of 9.8% obtained at operating frequency 2.1GHz. This proposed filter configuration effectively reduced the cost of assembly and the difficulty of integration associated with other circuits. The concept is very attractive for using in low cost, low insertion loss and high Q production of wireless filter application.

TDEFIE-PMCHW Method Combined With an Adaptive Marching-On-in-Order Procedure for Studying on Time- and Frequency-Domain Responses of Some Composite Structures

Abstract: One effective method, based on time-domain PMCHW (Poggio, Miller, Chang, Harrington, and Wu) integral equation, is presented for studying on time- and frequency-domain electromagnetic responses of some composite structures. A set of derived equations is solved by an adaptive marching-on-in-order (MOO) procedure. During its implementation, dielectric parts of the composite structure are described by the PMCHW equations, and its metallic parts are governed by the time-domain electric field integral equations, where temporal basis of the Laguerre polynomials are employed for both of them. As an example of composite microstrip patch structure, its dielectric- metallic junction is handled using an appropriate combination of the full RWG basis functions so as to obtain high computational accuracy, and one MOO acceleration scheme is employed for accelerating the temporal convolution effectively. Numerical results are given to demonstrate efficiency as well as accuracy of our proposed method used for capturing electromagnetic responses of some typical composite structures, with their transient current responses, far-field distributions, radar cross sections, and directivities predicted successfully.

Improved FDTD method for studying on graphene frequency selective surface (GFSS) characteristics for nanoelectromagnetics applications

Abstract: A generalized recursive convolution (RC) FDTD method integrated with subcell technique is proposed for studying on transmission and reflection characteristics of cross-shape graphene frequency selective surface (GFSS) which is biased by an electrostatic field. This improved method is very flexible for efficiently modelling single and even multi-layer dispersive “thin” nano layers together with other dispersive media, which can be used for the development of some novel nano structures for EMC applications operating at very high frequencies. Parametric studies are performed to demonstrate the GFSS performance up to THz band which is controllable or adjusted by the applied electrostatic field.

Modeling and characterization of carbon-based heterogeneous interconnects for 3-D ICs

Abstract: In this paper, one novel heterogeneous interconnect scheme, which combines the graphene-built horizontal interconnects and vertical through silicon carbon nanotube bundle vias (TS-CNTBV), is proposed and investigated theoretically The equivalent circuit models for them are presented and combined The anomalous skin effect (ASE) is treated appropriately for graphene-built interconnects The distributed parameters as well as transmission characteristics are obtained numerically This work provides some useful information about carbon-based interconnects where the advantages of carbon nanomaterials can be exploited for the development of 3-D ICs

Enhanced conformal FDTD method for predicting transient responses of arbitrary PEC wedges illuminated by an electromagnetic pulse

Abstract: One enhanced conformal FDTD method is proposed for characterizing transient responses of arbitrary PEC wedges illuminated by an electromagnetic pulse (EMP), and one low-cost modified technique is introduced for effectively suppressing numerical dispersion error with much high accuracy achieved. Excellent agreement is also obtained between our captured diffraction field of the wedge and that of uniform theory of diffraction (UTD). Further, numerical investigation is performed for predicting the EMP responses of PEC wedges with different geometries, different incident EMP directions and different observation points, etc. We would like to say that this study will be useful for the design of EMC and electromagnetic protection for ship or aircraft platform.

One-step leapfrog ADI-FDTD method for anisotropic magnetized plasma

Abstract: A one-step leapfrog alternating-direction-implicit finite-difference time-domain (ADI-FDTD) method is proposed for modelling anisotropic magnetized plasma. Two ways to derive the differential equations are presented: one from the conventional ADI-FDTD method directly and the other from the perturbation theory. The stability of the proposed method is verified numerically. In particular, its computational efficiency in modeling anisotropic magnetized plasma is shown.

Design of a novel reconfigurable Sierpinski fractal graphene antenna operating at THz band

Abstract: A novel reconfigurable fractal graphene antenna model operating at THz band is presented in this paper, where the frequency-dependent property of graphene conductivity is implemented into our simulation. In the development of such Sierpinski fractal antenna with self-similarity, we use graphene to fill its slot parts so as to achieve our desired reconfigurable capability. Some numerical results are given to show the radiation performance of our proposed graphene antenna model, with experiment being done so as to verify our design.

Investigation on gyrotropic effect of magnetically biased graphene sheet in rectangular waveguide

Abstract: In this paper, the transmission and reflection characteristics of a rectangular waveguide loaded with a graphene sheet is investigated theoretically, where the graphene is biased with a static magnetic field and shows gyrotropy. According to the nonreciprocal S-parameters of the composite structure, significant coupling and conversion are observed among different guided modes. In order to clearly provide its physical laws, the influences of operating frequency, biased magnetic field and chemical potential of the graphene sheet are also explored carefully.

Shielding cover effects on the RF performance of LDMOSFET power amplifier for WCDMA application

Abstract: Shielding cover effects on the RF performance of LDMOSFET power amplifier (PA) is investigated. In our measurement, the PA cover is made of aluminum, with its height adjusted from 8.4 to 14.4mm which are widely used in current wireless communication application. The input-output responses of several PA samples with cover are measured and compared for different cover heights. Both experiment and simulation show that as the cover height is reduced, the PA performance is degraded, but its power efficiency and linearity are not varied approximately. Further, it is found that, even the cover height is decreased, but through careful optimizing of its internal impedance matching networks consisting of multiple bonding wires, the PA performance can be improved effectively. This research can provide some useful design guidance for the development of compact and miniaturized PA module with high performance.

Numerical dispersion optimized leapfrog ADI-FDTD method and its application for capturing surface current distributions of complex objects illuminated by an electromagnetic pulse (EMP)

Abstract: A numerical dispersion optimized leapfrog alternating direction implicit finite-difference time-domain (ADI-FDTD) method is proposed in this paper, where a set of artificial anisotropic parameters is introduced into its implementation. Under such circumstances, its numerical dispersion can be suppressed efficiently. Some numerical experiments are performed and compared with the original leapfrog ADI-FDTD method, it is shown that our proposed method can achieve much higher computational accuracy. Further, such method is adopted for predicting surface current distributions of some 3-D complex objects illuminated by an electromagnetic pulse (EMP), such as a tank and an aircraft, etc., and good agreement is obtained in comparison with commercial software.

Improved FDTD simulation for predicting transmission characteristics of graphene and solid plasma composite with a biased magnetic field

Abstract: One generalized piecewise linear recursive convolution (PLRC) FDTD method is proposed for predicting transmission characteristics of graphene and solid plasma composite biased by a magnetic field. This improved method is very flexiable for efficiently modeling single and even multi-layer anisotropic and dispersive “thin” layers together with other anisotropic media, which can be used for the development of some novel structures for RF applications. Parametic studies are performed to demonstrate double-gyrotropy effects in both graphene and solid plasma on the transmission coefficient of the normally incident plane wave, and it can be controlled or adjusted by the biasing magnetic field. This research can provide some fundamental information about the interaction of an electromagnetic wave with nonreciprocal graphene-based composites.

Electrical modeling of multi-walled carbon nanotube (MWCNT)-based capacitors for high-density RF integration

Abstract: Modeling of multi-walled carbon nanotube (MWCNT)-based capacitors is performed in this paper. Their equivalent circuit model is modified with the impacts of quantum capacitance as well as kinetic inductance treated in an appropriate manner. Further, both effective capacitance and quality factor of the MWCNT-based capacitors are predicted even at ultrahigh frequencies, and their self-resonance frequencies are also captured successfully.

Electro-Thermal-Stress analysis of a LDMOS FET Breakdown under High Power Microwave pulses

Abstract: This paper presents thermal and stress breakdown effects in a LDMOS FET under the impact of High Power Microwave pulses. Experimental investigations of the LDMOS FET-based power amplifier (PA) are performed under HPM pulses. The Electro-Thermal- Stress (E-T-S) breakdown of the device is observed. To characterize temperature and stress distribution of the LDMOS FET, we developed a physical electro-thermal-stress model using time-domain finite-element method. Simulations are performed and compared with measurements. This research can provide useful knowledge for understanding the reliability of RF power devices.

Design of a compact rat-race coupler employing electromagnetic bandgap (EBG)-loaded and composite right/left-handed (CRLH) half-mode substrate integrated waveguides (HMSIWs)

Abstract: A new type of rat-race coupler, based on electromagnetic bandgap (EBG)-loaded half-mode substrate integrated waveguide (HMSIW) and composite right/left-handed (CRLH) HMSIW, has been proposed and investigated comprehensively It consists of three sections of EBG-loaded HMSIWs with 90° phase delay and one section of CRLH HMSIW with −90° phase advance Due to the evanescent-mode of EBG-loaded HMSIW and the backward behavior of the CRLH HMSIW in the left-handed region, the size of such a miniaturized rat-race coupler is reduced about 657% in comparison with its conventional counterpart The rat-race coupler with the central frequency of 55 GHz has been designed and fabricated so as to validate our method, and its good performance is demonstrated by both simulated and measured results

A Novel Conformal Surface Current Technique for Large Problems Based on High-Performance Parallel FDTD Method

Abstract: Solution of electrically large problems such as scattering and diffraction by large objects—e.g., missiles, ships, and aircraft—is of considerable interest today. The finite-difference time-domain (FDTD) method is a versatile tool that has been extensively applied to the solution of these large problems. However, since the FDTD algorithm usually works with a Cartesian grid, it is not very well suited for extracting information on the induced current distribution on the surface of the object. Given this background, our objective in this letter is to describe a novel conformal technique, applied in conjunction with the high-performance parallel FDTD method, which extracts and displays the information of the surface on an arbitrarily shaped object in an accurate and efficient manner. Finally, some typical numerical examples are given to demonstrate the capability of our developed conformal technique.

Novel parallel meshing technique implemented into parallel FDTD simulation using function language for solving electrically large and complex EMC problems

Abstract: It is well known that in all FDTD simulations for predicting electromagnetic responses of various two- and three-dimensional structures, we always need to generate their appropriate meshes. In particular, for conformal and other enhanced FDTD algorithms, appropriate meshing is very important and it is directly related to the simulation accuracy. The real-world model, such as aircraft and ship platform etc., often contains millions of surface patches, thus parallelization for meshing is an effective way for improving the FDTD simulation efficiency. In this paper, one complete parallelized meshing technique combined with fast parallel FDTD computation workflow is developed and several testing examples are presented for validating our algorithm. With its successful implementation, surface current distributions overall an aircraft and a warship platform with aircrafts in the presence of an electromagnetic pulse are captured and examined, respectively. We would like to emphasize that high parallel efficiency is achieved during our simulations for solving a lot of EMC problems.

Effect of supporting substrate on mode characteristics of graphene-loaded rectangular waveguide

Abstract: The transmission, reflection and mode conversion characteristics of a rectangular waveguide loaded with graphene sheets on substrates are investigated in this article. The effect of supporting substrate on the mode characteristics corresponding to H10- and H01-modes is studied, with equivalent transfer matrices and multiport network. The theoretical results for the cases with single and multiple periods are both provided and discussed.