Nonlinear optical properties and morphologies of vanadyl‐phthalocyanine thin films prepared on polyethylene‐terephthalate film

Vanadyl phthalocyanine (VOPc) crystal thin films were prepared on poly(ethylene terephthalate) (PET) film. The VOPc film prepared on PET substrate at 120 °C had Phase II. The third harmonic (TH) intensity of the VOPc film was measured by the marker fringe method. The third optical susceptibility (χ⁽³⁾) estimated from TH intensity is 3.5 × 10^?9 esu. The transition from Phase I to Phase II of the VOPc film was enhanced with corona charging. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(2): 36–43, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10022     

Fabrication of high‐quality two‐dimensional photonic crystals based on porous alumina

We fabricated porous alumina templates with a well‐ordered pore array by a pre‐triggered anodization method. The arrangement of pores in the fabricated templates was set by a Ni‐dot stamper. The structure of the templates was analyzed by field emission scanning electron microscopy (FESEM), two‐dimensional Fourier transformation of FESEM images and optical means. It was found that the porous alumina templates have a high‐quality, extended, two‐dimensional hexagonal lattice, which can be used in the fabrication of two‐dimensional magnetophotonic crystals (2D‐MPCs). © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Time‐domain sensitivity analysis of planar structures using first‐order one‐way wave‐equation boundaries

An efficient adjoint variable method technique is developed for time‐domain sensitivity analysis of planar structures with transmission‐line modeling complemented by a first‐order one‐way wave‐equation absorbing boundaries. A backward‐running adjoint simulation is derived and solved. The validity of the technique is illustrated through three microstrip circuits. The examples demonstrate the efficiency and accuracy of the technique in comparison with the classical finite‐difference approaches to the estimation of the response sensitivities. Copyright © 2007 John Wiley & Sons, Ltd.     

Crank‐shaped and Y‐shaped through‐hole interconnections filled with Au‐Sn solder

Crank‐shaped and Y‐shaped through‐hole interconnections (THI) filled with Au‐Sn solder are demonstrated in this study. They are expected to realize a higher‐density wafer‐level package (WLP) for electrical devices including the fields of MEMS (Micro Electro‐Mechanical Systems) and MOEMS (Micro Optical Electro‐Mechanical Systems) compared with conventional WLP using THI consisting of straight through‐holes. In this paper, formation techniques for crank‐shaped and Y‐shaped THI are described. In order to make crank‐shaped and Y‐shaped through‐holes in a substrate, both femtosecond laser irradiation and wet chemical etching are used. Crank‐shaped through‐holes with an 80‐μm opening and 400 μm deep have also been achieved. Gold (Au)‐tin (Sn) solder was filled into the holes using the molten metal suction method (MMSM). Airtightness of the THI was examined using the helium leakage test, and the estimated leakage rate was less than 1.0 × 10^?9 Pa·m³/s, which is sufficient for use in WLP applications. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(1): 54–62, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com) . DOI 10.1002/eej.21134     

Dynamics of charge‐pump phase‐locked loops

Certain problems in the existing treatment of the stability of charge‐pump phase‐locked loops are identified and addressed in this work. New results concerning the instability, stability, and asymptotic stability of charge‐pump phase‐locked loops are obtained by means of Lyapunov's direct and indirect methods. Closer consideration of the local dynamics provides further insight into the system's patterns of behavior. In particular, the influence of circuit parameters on the nature of the steady‐state orbits is investigated. Copyright © 2012 John Wiley & Sons, Ltd.     

Parallel FETI‐DP algorithm for efficient simulation of large‐scale EM problems

An efficient parallelization of the dual‐primal finite‐element tearing and interconnecting (FETI‐DP) algorithm is presented for large‐scale electromagnetic simulations. As a nonoverlapping domain decomposition method, the FETI‐DP algorithm formulates a global interface problem, whose iterative solution is accelerated with a solution of a global corner problem. To achieve a good load balance for parallel computation, the original computational domain is decomposed into subdomains with similar sizes and shapes. The subdomains are then distributed to processors based on their close proximity to minimize inter‐processor communication. The parallel generalized minimal residual method, enhanced with the iterative classical Gram‐Schmidt orthogonalization scheme to reduce global communication, is adopted to solve the global interface problem with a fast convergence rate. The global corner‐related coarse problem is solved iteratively with a parallel communication‐avoiding biconjugate gradient stabilized method to minimize global communication, and its convergence is accelerated by a diagonal preconditioner constructed from the coarse system matrix. To alleviate neighboring communication overhead, the non‐blocking communication approach is employed in both generalized minimal residual and communication‐avoiding biconjugate gradient stabilized iterative solutions. Three numerical examples are presented to demonstrate the accuracy, scalability, and capability of the proposed parallel FETI‐DP algorithm for electromagnetic modeling of general objects and antenna arrays. Copyright © 2016 John Wiley & Sons, Ltd.     

Device‐partition method using equivalent circuit model in two‐dimensional device simulation

In order to accomplish two‐dimensional device simulation with a large number of nodes, in this paper we propose the device‐partition method (DPM) to resolve the problem that the memory size of the simulation environment is insufficient. The idea of DPM is that the device can be divided into several parts and a matrix solver only solves one part at a time. DPM uses the iteration method to simulate the device. By continuous iteration, an accurate solution can be obtained. Hence, we use DPM to demonstrate the simulations of the MOSFET and the CMOS inverter. The simulation results of DPM and the coupled method (CM) are nearly approximate and correspond with the theory. Hence, DPM is a suitable method to develop a powerful simulation environment. Copyright © 2005 John Wiley & Sons, Ltd.     

Power‐efficient burst‐mode RF transmitter based on reference‐adaptive multilevel pulse‐width modulation

Burst‐mode operation of power amplifier (PA) based on multilevel pulse‐width modulation (MPWM) has been frequently discussed as a potential solution to achieve higher efficiency in radio frequency (RF) transmitters. In this paper, a novel multilevel PWM modulator is proposed that utilizes adaptive triangular reference waveforms. As compared with conventional MPWM modulators, the proposed architecture provides significant wider design space such that the efficiency of system can be effectively optimized. A general transmitter architecture based on the proposed concept is analyzed in terms of power efficiency. Efficiency optimization procedures are presented according to input magnitude statistics. Based on the proposed modulator, an optimized 2.4‐GHz RF transmitter is designed in a 0.18‐μm complementary metal‐oxide‐semiconductor (CMOS) process. The circuit‐level simulations show that it delivers 25.8‐dBm peak output power with 46.1% peak efficiency. For a 20‐MHz worldwide interoperability for microwave access (WiMAX) signal with 8.5‐dB peak‐to‐average‐power ratio (PAPR), this transmitter achieves 28.8% (average) efficiency at 17.3‐dBm (average) output power with an error vector magnitude (EVM) of 2.97% rms.     

Theory on asymmetrical coupled‐parallel‐line transmission and reflection zeros

This paper treats an innovative methodology on the synthesis mechanism of the coupled‐parallel‐line (CPL) transmission zero (TZ) and reflection zero (RZ). The CPL structure under study is configured as a reflection type distributed arbitrarily loaded stub circuits. On the basis of the equivalent Z‐matrix analysis, the CPL input impedance theoretical model is established. Mathematical analysis is performed to predict accurately the TZ and RZ frequency shifts in function of the CPL physical parameters. The input impedance behavioral model in function of asymmetrical CPL load parameters is determined. The TZ and RZ existence conditions are established. Then, the characteristic equations illustrating the TZ and RZ fundamental formulas in function of the CPL coupling coefficient and characteristic impedances are examined. Furthermore, innovative graphical representations of the TZ and RZ existence conditions in function of the CPL parameter ranges are explored. The developed CPL model was validated with different cases of simulated microstrip proof of concept. As expected, a good correlation between the TZ and RZ frequency shifts from the analytical calculations and simulations is obtained. The developed CPL model is useful for the TZ and RZ frequency shifts fast monitoring during the Radio Frequency (RF)/microwave circuit design phase. Copyright © 2017 John Wiley & Sons, Ltd.     

Nonlinear dynamics of divide‐by‐two injection‐locked frequency dividers in locked operation mode

A method for analyzing the nonlinear dynamics of the injection‐locked frequency dividers in synchronized operation mode is presented, including the stability analysis of locked states. We use a specific divide‐by‐two circuit, namely a differential LC CMOS divider with a complementary topology, as a guideline for presentation, showing that the sizing of the devices significantly affects the synchronization mechanism of the divider, which exhibits a very rich dynamical behavior. We provide closed‐form expressions to determine the amplitude and the phase in the locked state, as well as the locking range, leading to accurate results, which are validated by numerical simulations. The presented analysis of the frequency divider dynamics enables us to establish that stable locked oscillations occur on the whole locking range predicted by the well‐known Adler's equation and that these are possible also beyond that range. Copyright © 2013 John Wiley & Sons, Ltd.     

Thermally stimulated current and thermally stimulated charge distribution in electron‐beam‐irradiated PMMA

The relationship between the external current J_ter(t), the conduction current J_c(x, t), and the displacement current ϵ∂E(x, T)/∂t of an electron‐beam‐irradiated PMMA is discussed in terms of measurements of the thermally stimulated current (TSC) and the thermally stimulated space charge distribution (TS‐SCD). ϵ∂E(x, T)/∂t is calculated from TS‐SCD measurements obtained with an improved pulsed electroacoustic (PEA) system. By virtue of the conservation of charge, J_c(x, t) is easily calculated from the measured J_ter(t) and the calculated ϵ∂E(x, T)/∂t. In this report, an approach to the conduction current analysis using the theory of conservation of charge is described and an analysis of the conduction current in an electron‐beam‐irradiated PMMA is introduced as a typical example. © 1999 Scripta Technica, Electr Eng Jpn, 128(2): 1–6, 1999     

Experimental Verification of a Front‐to‐Front (FTF) System Consisting of Two Modular Multilevel Cascade Converters Based on Double‐Star Chopper Cells

This paper presents an experimental discussion on modular multilevel cascade converters based on double‐star chopper cells (MMCC‐DSCC). Hereinafter, a single MMCC‐DSCC is referred to simply as a “DSCC”. A couple of DSCCs are used to form a front‐to‐front (FTF) system capable of dc voltage matching and galvanic isolation between two dc grids. The FTF system can be considered as a dc–ac–dc power conversion system including an ac‐link high‐power transformer. The higher the ac‐link frequency, the smaller and lighter are the ac‐link transformer and dc capacitors. When the so‐called “phase‐shifted‐carrier PWM” is applied to the DSCC, theoretical analysis and computer simulation have confirmed that a ratio of the carrier frequency with respect to the ac‐link frequency can be reduced to 5/2. This paper designs, constructs, and tests a 400‐Vdc 10‐kW downscaled FTF system with a carrier frequency of 450 Hz and an ac‐link frequency of 180 Hz, where their ratio is 5/2. Experimental waveforms obtained from the downscaled system are compared with simulated ones obtained from a software package, PSCAD/EMTDC, under the same operating and circuit conditions. They agree well each other not only under steady states but also under transient states.     

Two‐graph analysis of pathological equivalent networks

Recently, abstract current mirror and voltage mirror elements have been proposed for behavioral modeling of active analog blocks. Such artificial elements and the traditionally used nullor element together are called pathological elements in the literature. Pathological elements are very useful in modeling and analysis of active network. Hence, researchers have been motivated to study symbolic analysis methods for networks containing pathological elements. However, so far, only nodal admittance matrix analysis has been formulated. In this work, an alternative two‐graph method is formulated, which has the advantage of providing a compact intermediate form for subsequent symbolic term generation. With a compact two‐graph representation, either a matrix method or a tree enumeration method can be employed. For completeness, the classical two‐graph theory has been extended in this paper to encompass all four types of dependent sources and all pathological elements. Illustrative examples are presented to demonstrate the principle of compact symbolic term generation by the presented two‐graph method. Copyright © 2014 John Wiley & Sons, Ltd.     

Mode‐matching analysis of a spit‐circular cavity resonator for measurement of the dielectric constant for film on a substrate

In this paper, we apply the mode‐matching technique (eigenmode expansion) to formulate an analytical model for a split cylindrical cavity resonator with a thick ceramic film layer sandwiched between two‐layer alumina substrates. We then compute the resonant frequencies with the TE₀₁₁ mode with an eigenvalue problem approach using the model formula. The quality factor (Q ‐factor) of the resonator is also calculated by applying the perturbation method to the analytical model. The validity of the proposed analytical technique is confirmed by applying this method to the estimation of permittivity of thick films as an inverse problem. Ceramic films (2 µm thickness) were synthesized using a chemical solution method onto 200‐µm‐thick, 50‐mm‐diameter alumina substrates. The complex permittivity of the films was then determined using the TE₀₁₁ mode split cylindrical cavity resonator in the 10‐GHz band. The extent of the edge effect at a sample insertion space was evaluated by comparing the estimated results through TE wave analysis using the mode‐matching method when the transverse resonance technique and the perturbation method were applied to calculate the resonant frequency and the dielectric Q ‐factor. The results obtained indicate that a difference of 0.153% in the permittivity of the alumina substrate causes differences of 6.10 and 3.75% in the measured permittivity and loss tangent, respectively, of 2‐µm‐thick ceramic film with a permittivity of ∼50. Differences in permittivity and loss tangent were more pronounced with thinner films. It was also confirmed that the estimated results for permittivity and the loss tangent values of these ceramic films were affected by the estimated permittivity value of the alumina substrate. © 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

On the development of efficient FDTD‐PML formulations for general dispersive media

A novel implementation of the perfectly matched layer (PML) absorbing boundary condition (ABC) to terminate the finite‐difference time‐domain (FDTD) algorithm for general dispersive and negative index materials is presented. The proposed formulation also adopts the complex frequency‐shifted (CFS) approach, involves simple FDTD expressions and avoids complex arithmetic. Several FDTD‐PML simulations with different parameters are conducted for the termination of various dispersive media validating the stability, accuracy and effectiveness of the schemes and indicating the advantage of the CFS‐PML. Copyright © 2008 John Wiley & Sons, Ltd.     

Operation analysis of quasi‐resonant,high‐frequency transformer link dc–ac converters applied to phase‐shift PWM control on the secondary side

In recent years, the soft‐switching techniques have attracted attention for their peculiar advantages such as low switching loss, high power density, EMI/RFI noise reduction, and so on. The authors have previously reported on a quasi‐resonant dc–dc converter using new phase‐shift PWM control scheme. By using the proposed control scheme, circulating current is eliminated and ZVS (Zero Voltage Switching) is achieved with small commutating current. As a result, the conduction losses caused by their currents are substantially reduced. In this paper, the authors apply a proposed control scheme to a quasi‐resonant high‐frequency transformer link dc–ac converter. As a result, all switching devises in this dc–ac converter can achieve soft switching with small commutating current irrespective of inverter mode and rectifier mode. Its operating principle and unique features are described as compared with the symmetrical control scheme of dc–ac converter. Operating performance of this dc–ac converter in the steady state is illustrated by means of simulation results. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 88–98, 2000     

Preparation and functions of conductive polymer/insulating polymer composite films using molecular self‐assembly

By exposing low‐density polyethylene to an atmosphere of fuming sulfuric acid, sulfonated low‐density polyethylenes (SPE) were prepared and the degree of surface sulfonation of the treated film was determined from the weight increase per unit area. Polypyrrole (PPy) films on the surface of SPE were grown by molecular self‐assembly and the properties of PPy/SPE composite films were investigated. Functional applications of PPy/SPE composite films are proposed, with particular attention to the movement properties of actuators using PPy/SPE composite films. © 1999 Scripta Technica, Electr Eng Jpn, 128(1): 1–8, 1999     

Sparse approximate inverse preconditioning of deflated block‐GMRES algorithm for the fast monostatic RCS calculation

A sparse approximate inverse (SAI) preconditioning of deflated block‐generalized minimal residual (GMRES) algorithm is proposed to solve large dense linear systems with multiple right‐hand sides arising from monostatic radar cross section (RCS) calculations. The multilevel fast multipole method (MLFMM) is used to accelerate the matrix–vector product operations, and the SAI preconditioning technique is employed to speed up the convergence rate of block‐GMRES (BGMRES) iterations. The main purpose of this study is to show that the convergence rate of the SAI preconditioned BGMRES method can be significantly improved by deflating a few smallest eigenvalues. Numerical experiments indicate that the combined effect of the SAI preconditioning technique that clusters most of eigenvalues to one, coupled with the deflation technique that shifts the rest of the smallest eigenvalues in the spectrum, can be very beneficial in the MLFMM, thus reducing the overall simulation time substantially. Copyright © 2008 John Wiley & Sons, Ltd.