A nonlinear and dispersive APML ABC for the FD-TD methods

We have developed a modified anisotropic perfectly matched layer (APML) absorbing boundary condition (ABC) for the finite-difference time-domain (FD-TD) analysis of nonlinear and dispersive media. The formulation is a simple modification to the original nonsplit APML, and retains the robustness and the simple implementation in the FD-TD and the higher-order schemes. The proposed ABC has a broad area of application, and is especially suitable for the analysis of nonlinear optical waveguide problems.     

An estimation method for the free-space antenna factor of VHF EMI antennas

A novel numerical method is developed for theoretically estimating the free-space antenna factor of an electromagnetic interference (EMI) antenna, especially for the very high frequency (VHF) range where traditional methods are difficult to apply. It requires conventional EMI antenna calibration such as the standard antenna method to obtain the antenna factor of an antenna under calibration as a function of the antenna height. Then, a nonlinear least-squares method is applied to the calibration results to estimate the free-space antenna factor. It is found that the proposed method can yield more accurate estimates of the free-space antenna factor than the averaging method. Attainable accuracy of this method is better than 0.2 dB for tuned dipole antennas and 0.1 dB for biconical antennas and biconi-log antennas. The paper outlines the theoretical background and the validity of this method, with the attainable accuracy demonstrated using method of moments simulations.     

High-Temperature Formation Phases and Crystal Structure of Hot-Pressed Thermoelectric CuGaTe<Subscript>2</Subscript> with Chalcopyrite-Type Structure

Polycrystalline CuGaTe₂ with a chalcopyrite-type structure consolidated by hot-pressing is a potential candidate as a medium-temperature thermoelectric (TE) material. However, its high-temperature formation phases have rarely been reported to date. Here, we investigated the temperature-dependent formation phases and crystal structure at 300–800 K of hot-pressed CuGaTe₂. From synchrotron x-ray diffraction data and crystal structure analysis of the heating and cooling processes, it was clarified that a certain amount of impurity phases, such as Te and CuTe, precipitated from the CuGaTe₂ matrix when the temperature was increased (to 500–650 K). This is the temperature range where CuGaTe₂ has been reported to show high TE performance. After CuGaTe₂ was heated to 800 K, such impurity phases remained, even when cooled to room temperature. They also affected the tetragonal distortion and the x-coordinate of Te in the CuGaTe₂ matrix, probably due to deficiencies of Cu and Te in the matrix. Our results reveal detailed information on the formation phases of CuGaTe₂ at high temperature and thus provide insight for evaluation of its high-temperature stability and transport properties.     

A 1-Gb/s/pin 512-Mb DDRII SDRAM using a digital DLL and a slew-rate-controlled output buffer

A 1-Gb/s/pin 512-Mb DDRII SDRAM has been developed using a digital delay-locked loop (DLL) and a slew-rate-controlled output buffer. The digital DLL has a frequency divider for DLL input, performs at an operating frequency of up to 500 MHz at 1.6 V, and provides internal clocking with 50% duty-cycle correction. The DLL has a current-mirror-type interpolator, which enables a resolution as high as 14 ps, needs no standby current, and can operate at voltages as low as 0.8 V. The slew-rate impedance-controlled output buffer circuit reduces the output skew from 107 to 10 ps. This SDRAM was tested using a 0.13-/spl mu/m 126.5-mm/sup 2/ 512-Mb chip.     

A novel on-chip electrostatic discharge (ESD) protection withcommon discharge line for high-speed CMOS LSIs

A novel on-chip electrostatic discharge (ESD) protection for high-speed CMOS LSI's that operate at higher than 500 MHz has been developed. Introduction of a newly developed common discharge line (CDL) can completely eliminate the protection device influence on the inner circuit operation. This enables minimization of the I/O capacitance by shrinking the dimension of the output transistor, which also serves as a protection device in conventional devices. This new protection (CDL protection) was applied to a high-speed DRAM of which I/O pin capacitance specification is 2 pF. As a result, the ESD tolerance of 4 kV for the charged device model test, 4 kV for the human body model test, and 700 V for the machine model test were obtained. In addition, the DRAM data rate higher than 660 MHz at room temperature was achieved. The results show significant improvement for both ESD and the I/O capacitance, compared with the conventional structure     

An organic infrared electroluminescent diode utilizing aphthalocyanine film

Electroluminescent (EL) diodes utilizing metal-free phthalocyanine (H₂Pc) have been fabricated by the vacuum evaporation method. The EL characteristics of the diodes depending upon the metal cathode and the characteristics of the diodes with the coevaporated layer with 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) have been investigated. We have demonstrated the infrared electroluminescence originated from the radiative transition corresponding to the Q band of H₂Pc by taking the energy band structure into consideration     

Impact of Dynamic Interlayer Interactions on Thermal Conductivity of Ca3Co4O9

The phonon thermal conductivity of misfit-layered Ca₃Co₄O₉ has been calculated by perturbed molecular dynamics using a classical force field. Detailed numerical analyses reveal that, in spite of its smaller cross-sectional area, the CoO₂ layer transports more heat than the thicker rock salt (RS) layer, although its local thermal conduction is more suppressed than in another layered cobaltite, Na _x CoO₂. The origins of these differences have been elucidated through careful examination of the atomic arrangements in each layer. Since thermal conduction in the RS layer can be reduced without deteriorating electronic properties for which the CoO₂ layer is responsible, it is suggested that the RS layer should be modified to further suppress the overall in-plane thermal conductivity. Computational experiments with increasing number of Ca–O planes in the RS layer showed the opposite trend to what can be predicted based on the misfit between two dissimilar layers. Further analyses to reveal the origin of these unexpected results provide yet another strategy to further decrease the thermal conductivity, namely to control the dynamic interference between atoms across the interface between two layers.     

Artifact reduction using reliability reasoning for image generation of FTV

In this paper, we present a new view synthesis method in multiview camera configurations of Free viewpoint TV (FTV) where potential depth errors are considered. The emphasis is on the artifacts eliminating for photorealistic synthesis especially near object boundaries. In contrast to conventional techniques which ignore geometry errors, we first categorize the artifact cases and depth modes. Furthermore, this paper infers the complementarity principle of the artifacts from left and right references. This complementarity guarantees the effectiveness of our reliability-based synthesis. The reliability reasoning is crucial for artifacts reduction. The reliable and unreliable areas from different views can be correctly labeled. Then artifacts caused by unreliable pixels from one reference can be replaced by the reliable pixels from the other reference. As a final result, artifacts of novel view are demonstrated to be significantly reduced on different multiview sequences.     

Integrated Wavelength-Insensitive Differential Laser Doppler Velocimeter Using Planar Lightwave Circuit

In this paper, a design of an integrated wavelength-insensitive laser Doppler velocimeter (LDV) has been proposed using planar lightwave circuit (PLC). The proposed LDV uses arrayed waveguide gratings (AWGs) that can be fabricated using PLC technology. Its characteristics are simulated using a design model based on grating equations for AWGs. The simulation results indicate that wavelength-insensitive operation can be almost obtained by optimizing the design parameters of the proposed structure without assembly of bulk diffractive gratings or other optical elements.