bluuebunny/crossref_metadata_2025_split huggingface dataset:
A parallel divider for architecture numbers of arbitrary word length
Authors: Nakamura Tsugio , Kasahara Hiroshi 
Published: July 2007

AbstractThe high‐speed and highly accurate arithmetic unit is becoming more important. Especially, one factor that determines the system performance is the execution of the multiplication/division, which arises frequently and takes a long computation time. The most appropriate idea in improving the speed is the parallel hardware architecture.Often in the system design, the capacity of the initially designed arithmetic unit becomes insufficient due to the change of specification and the upgrading of the system function after the design making the circuit redesign necessary. Especially, in the case of the divider, such a system redesign is not easy since it cannot be used if the number exceeds the word length. If the number exceeds the operational capacity even by a bit in the divider, it is difficult to cope with the requirement, even if a memory or an external circuit is added. Hence, there is less advantage in fabricating a dedicated integrated circuit (IC) and there are only a few examples of the one‐chip divider.The high‐speed dedicated arithmetic unit includes digital signal processing (DSP) circuitry and a DSP coprocessor, but the division is executed by the software since it is not advantageous to include the divider. This requires a long computation time.From such a viewpoint, this paper proposes an architecture for the parallel divider which can cope with any requirement for the accuracy only by employing several similar dividers. Detailed problems in the expansion of the operational accuracy are discussed, and the proposed divider architecture is described. The one‐chip implementation also is discussed.By this structure, an advantage is produced to prepare the dedicated divider, and the cheap, efficient and high‐speed division can be realized by a relatively small‐scale divider. The proposed divider will be applied widely, not only to the general scientific computations but also to various control systems, signal processing, and computer communication.
A solid electrolytic paper battery containing electroconductive polymers
Authors: Osawa Toshiyuki , Kimura Okitoshi , Kabata Toshiyuki , Samura Tetsuya , Yoshino Katsumi 
Published: July 2007

AbstractThis paper describes a solid paper rechargeable battery using an electrolytically polymerized polyaniline film as the electrode and nonaqueous electrolyte gel with high ionic conductivity as the solid polymer electrolyte.A high‐strength fibril polyaniline film with a tensile strength of 5 kgf/cm2 was formed by electrolytic polymerization in tetrafluoro‐boric acid. It was found that the film had an excellent oxidation‐reduction characteristic in the solid polymer electrolyte. In addition, by bridging a highly concentrated nonaqueous electrolyte in monomer, the ionic conductivity of the solid polymer electrolyte was comparable with that of liquid electrolyte.Since the solid polymer electrolyte was fabricated using a solution with low viscosity, a solid paper lithium rechargeable battery with a highly efficient discharging property was realized by combining a polyaniline film.
Properties of GaAs1 ‐ xPx epitaxial films prepared by ion beam sputter deposition
Authors: Takaishi Yoshihiro , Itoh Tadatugu 
Published: July 2007

AbstractMany works on heteroepitaxial growth of III—V compound semiconductors on an Si substrate have been reported. However, many problems must be solved. In this study, GaAs1 ‐ xPx heteroepitaxial growth on Si and GaAs substrates at 250°C was carried out using the ion beam sputter‐deposition method. The dependencies of crystallinity and electrical properties of deposited films on x were investigated.The film composition was investigated by evaluating the core level spectra for As‐3d and P—2p levels in X‐ray photoelectron spectroscopy. In this evaluation, the composition was independent of the kind of substrate and film crystallinity.When a polycrystalline GaAs target was sputtered by Xe ion beam, the deposited film was neither single‐crystalline nor stoichiometric. When a mixture of Xe and PH3 ion beams was used, the deposited film was stoichiometric and RBS revealed that the film had excellent crystallinity. When a film was deposited on a GaAs substrate, the carrier mobility was higher than when it was deposited on Si.
Three‐dimensional memory LSI with optical interconnections
Authors: Koyanagi Mitsumasa , Takata Hirokazu , Okano Hiroshi , Yokoyama Shin 
Published: July 2007

AbstractAs devices are miniaturized and device operation speed increases by the progress of fine fabrication technology, the problems associated with interconnections such as interconnect delay and crosstalk are becoming important. Therefore, an optical connection as a new interconnect technique to solve these interconnection related problems is becoming noticed. On the other hand, three‐dimensional LSIs are again becoming noticed as an LSI to overcome the limitations of high integration and to incorporate new functions such as parallel processing function. Consequently, this paper examines the possibility of LSI with new function surpassing the present LSIs by combining the optical interconnection and three‐dimensional LSIs by combining the optical interconnection and three‐dimensional LSI. As an example of this kind of LSI, a three‐dimensional optically coupled common memory is described and the performance improvements are specifically shown by combining the optical interconnection and three‐dimensional LSI.
Single‐mode selection in pulsed lasers by injection seeding
Authors: Taira Takunori , Ogishi Hisataka , Kobayashi Takao 
Published: July 2007

AbstractA high‐power pulsed solid‐state laser for single‐mode oscillation is considered to be an important device in the new coherent optoelectronic fields such as super‐high‐resolution optics and heterodyne lidar. The injection seeding method has been utilized for single‐mode operation of high‐power Q‐switched lasers but the analyses of the basic characteristics and detailed experimental evaluation have not been carried out.In this paper, the conditions for single‐mode oscillation are analyzed using the multimode oscillation model and basic laser equations. Then the seeding characteristics are investigated using a laser diode (LD) pumped tunable wavelength single‐mode Nd : YVO4 microchip laser for the master laser and a pulsed Q‐switched Nd : YAG laser for the slave laser. As a result, it was found that single‐mode operation could be realized by the extremely low power of 0.9 μW which was close to the theoretical limit.In about 140 μm injection, the detuning width was 282 MHz which was close to the longitudinal mode separation. A seeding bandwidth of 71 GHz, which is almost half the fluorescence spectrum width of Nd : YAG, was realized.
Synthesis of biquadratic filters from current conveyors
Authors: Ikeda Katsuji , Tomita Yasushi 
Published: July 2007

AbstractThis paper describes a circuit configuration for a biquad filter which utilizes the second‐generation current conveyors (CC II) and is capable of synthesizing an arbitrary second‐order transfer function.The circuit is composed of a subblock circuit with two positive CC IIs and a differential input circuit with two positive CC IIs.The subblock circuit realizes a lowpass, high‐pass, and bandpass filter. Combining this with the differential input circuit produces an all‐pass and notch filter.Each filter has a high input impedance because its input is the Y terminal of the CC II and can be cascaded without a buffer. The quality factorQof the filter is determined by a ratio of passive elements, and its sensitivity to the passive element values is less than 0.5. These characteristics make the filters suitable for monolithic IC implementations. The effects of CC IIs voltage error ϵvand current error ϵion the filter characteristics were studied. It was found that the center frequency ωois independent of these errors,Qis affected only by ϵi, and the gain factor is a function of both ϵvand ϵi. Each filter was prototyped and was verified to operate as predicted.
Eigenstates of quantum wire structures with quasi‐bound geometry
Authors: Tsuji Yasuhidé , Hayata Kazuya , Koshiba Masanori 
Published: July 2007

AbstractThe eigenstate calculation of quantum‐wire mesoscopic structures with quasi‐bound geometry is reported. In this geometry, electron wave packets are confined quantum mechanically into an effective potential cavity created by the crossing of quantum wells.First, a variety of quasi‐bound quantum wire structures is presented. Subsequently, the eigenenergies and the eigenfunctions are analyzed numerically by using a two‐dimensional finite element method (2‐D FEM). In this analysis, effects due to the finiteness of the barrier height are studied in contrast to earlier simple models where the height is assumed to be infinite.Structural dependencies of the eigenstates show evidence of the critical parity selectivity for wave functions trapped in the quasi‐bound quantum wire system. A comparative study of analysis methods is made as well. Comparison of the results obtained by the 2‐D FEM with those by the weighted potential method shows the limitation of the latter reproduced approach to the present problem.
Discrete frequency sweeping of a semiconductor laser by temperature change and electrical feedback
Authors: Yoshizawa Akio , Iwasaki Takashi 
Published: July 2007

AbstractIn a constant interval multifrequency measurement to evaluate optical device characteristics, considering that a constant time is required for the measurement at each frequency, a sweeping method that maintains the frequency during the measurement is desirable. Although this stepwise frequency sweeping can be achieved by changing the injection current of the semiconductor laser, the possible sweep frequency range is much wider for the temperature change than for the current change.In this paper, noting this wideband sweeping range by the temperature change, two frequency sweeping methods are proposed. In these methods, the frequency changes stepwise for the temperature change proportional to the time that is easy to realize, and are verified and compared experimentally. In this method, a part of the laser light is incident on the Fabry‐Perot resonator with the temperature change, and the transmitted light signal or its differential signal is fed back into the injection current. As a result, the feedback signal corresponding to the resonant characteristics controls the shift of the resonance frequency by the temperature change in the neighborhood of the resonance frequency, realizing the frequency sweep that changes stepwise with the spacing equal to the free spectral range of the Fabry‐Perot resonator.
Analysis of lossy dielectric gratings using pseudo‐periodic green's function
Authors: Minami Kouji , Yamakita Jiro , Sawa Shinnosuke 
Published: July 2007

AbstractDifferential equation methods often are used for the analysis of the waves scattered by a dielectric grating. It is known that accurate numerical solutions can be obtained if the number of expansion terms of the spatial harmonics is increased. However, when the differential equation method is applied to a dielectric grating with an extremely large permittivity, the convergence speed of the solution becomes excessively slow in the TM wave analysis. Because of the increase of the computation time and the memory capacity, an analysis based on the differential equation method becomes difficult in practice.In this paper, it is shown that a boundary element method using Green's function satisfying the periodic condition is effective for the analysis. By introduction of pseudo‐periodic Green's function, the definition region for the integral equation is limited to the grating surface. In comparison to the boundary element method using the Hankel function, the number of linear equations is reduced. By means of numerical examples, it is shown that the convergence speed of the solution by the present method is faster and the computation time is significantly shorter than the solution by the differential equation method even in the TM wave analysis of a dielectric grating with a large loss.
Three‐dimensional finite element solutions of electron waveguide discontinuities
Authors: Gotoh Hitoshi , Koshiba Masanori 
Published: July 2007

AbstractA numerical approach based on the finite element method using tetrahedral elements is proposed for the three‐dimensional discontinuity in electron waveguides. A three‐dimensional finite element method is applied for a region containing a discontinuity with an arbitrary shape. The uniform waveguide region connected to the discontinuity is treated analytically. The reflection probability and transmission probability are calculated, in addition to the current density, by combining the finite element method and the analytical solution. The transmission characteristics of a rectangular cavity between two electron waveguides are examined. It is found that the transmission probability of the three‐dimensional structure is much different from that of the two‐dimensional one.
Finite element analysis of open‐type waveguides with homogeneous cladding by the use of multipole expansion
Authors: Ise Tomoyuki , Maruta Akihiro , Matsuhara Masanori 
Published: July 2007

AbstractOpen‐type waveguides with homogeneous cladding can be analyzed by the finite element method (FEM) with the multipole expansion method. In this paper, we propose a new connection method in which the fields described by the FEM and by the multipole expansion are combined at the connection boundary between the finìte inner region and the infinite outer region by using Galerkin method. By means of this method, we can analyze open‐type waveguides with higher accuracy and less amount of calculation than conventional FEM. In addition, there is no difficulty arising from spurious mode and no restriction between the number of the basis functions of the FEM and that of the multipole expansion functions on the connection boundary. The final matrix equation is symmetric. The validity and usefulness of the method has been demonstrated in the example of a rectangular dielectric waveguide and an elliptical fiber.
Fixed pattern noise from charge transfer loss in CCD imager
Authors: Ohkubo Yoshio , Ohmae Masanori , Ishikawa Kiyotsugu 
Published: July 2007

AbstractIt has been analyzed theoretically and verified experimentally that fixed pattern noise (FPN) is generated by the charge transfer loss when the charge in the CCD imager device generated by photoelectric conversion is imaged with a charge partitioning mode. This is done by removing the unnecessary nonsignal charge and reading out the signal charge. The result shows that the transfer loss due to the removal must be less than 10−4 to achieve even an ordinary picture quality with signal‐to‐noise (SN) ratio of 60 dB when the signal in the charge partitioning mode is one‐tenth the total charge. Furthermore, for a high‐quality image with SN ratio above 70 dB, the transfer loss in reading two kinds of charge must be less than 10−5 which is almost a perfect charge transfer.
Comparison of some characteristics of contact resistances on four kinds of Ag‐Pd alloy contacts with frequent switching of a 30V, 10A DC resistive circuit
Authors: Kubono Takayoshi 
Published: July 2007

AbstractTwenty‐four pairs of respective Ag, AgPd70/30, AgPd40/60, and Pd contacts are mounted on 24 miniature relays as pairs of electrical contact and switched the 30V, 10A DC resistive circuit on and off 100,000 times with the 1‐s closing period and 2‐s opening period. At each closing period, the contact resistance was measured with 10‐A circuit current.For all the materials, the histograms of the contact resistance averaged over 24 contact pairs from the start of opening/closing operations to 100 operations are clustered at approximately one location. The relation of the average contact resistance value among the four materials is the same as the relation of the resistivity and hardness. Therefore, the contact resistance at the initial stage of opening/closing operations is attributed to constriction resistance.For the case of Ag and Pd samples, the average contact resistance during the 100,000 operations depends little on the number of operations. Also, it is approximately the same as the average contact resistance during the initial 100 opening/closing operations. However, for the AgPd30% sample, the variation width increases with the switching operations. This is attributed to the fact that a selective evaporation of Ag from the contact surface during the arc discharge occurs and the alloy composition at the true contact surface changes repeatedly for each switching, with a resultant increase in variation of the average contact resistance.
Silicon surface nitrification using hydrogen and ammonia by hybrid excitation
Authors: Yamamoto Shigeichi , Migitaka Masatoshi 
Published: July 2007

AbstractA hybrid‐excitation technique using plasma excitation and photoexcitation in chemical vapor phase reaction has been developed. Using this technique, the silicon surface was nitrified in a mixture of ammonia (NH3) and hydrogen (H2) gases. First, a (100) Si substrate heated at 180°C was illuminated by ultraviolet ray (wavelengths: 184.9 nm and 253.7 nm) under NH3 atmosphere. At the same time, hydrogen radicals generated by decomposition of H2 gas in an RF (13.56 MHZ) inductive discharge tube were supplied to the substrate. Auger analysis indicated that the (100) Si surface up to about 1 nm in depth was nitrified and that the hybrid excitation was based on the synergy effect of photoexcitation and hydrogen radical excitation.Next, staggered‐structure thin‐film transistors were fabricated using amorphous Si whose surfaces nitrified by the foregoing method and the conventional plasma excitation method. It was found that when the hybrid‐excitation method was used, the field effect mobility was highest. In the gas analysis of hydrogen radical excitation, the presence of hydrazine was confirmed. Using this observation, the direct nitrification mechanism in the hybrid excitation was assumed.
A theoretical study of the I‐V characteristic distribution of polysilicon TFTs
Authors: Shinohara Toshiro , Tarui Yasuo 
Published: July 2007

AbstractA method to calculate the current‐voltage characteristics and its distribution of a polysilicon thin‐film transistor as a function of grain size has been developed. The simulation was based on a model for a potential distribution in each grain and the grain size distribution in a channel. The grain sizes (both observed and assumed) were used to set a grain size distribution in a channel, leading to determination of the number of grains and their location in the channel.The thermionic emission by taking into account the modulation of a grain potential barrier due to a gate‐drain electric field was calculated, and then the current‐voltage characteristics were determined by a self‐consistency method. Applying this method to a large grain polysilicon thin‐film transistor grown by a solid‐phase growth method, the static characteristic and its variation could be simulated successfully by having only two adjustable parameters of interface trap density and grain boundary trap density. Based on the present method, one can obtain a grain size distribution necessary to obtain desirable electric characteristics and thus can have a guideline for a process development.
Development of technologies for 2‐Gb/in2 areal density recording
Authors: Futamoto Masaaki , Kugiya Fumio 
Published: July 2007

AbstractHard disk technologies to realize 2‐Gb/in2 magnetic recording have been developed. An areal density is determined by a combination of a linear density and a track density.In this newly developed recording scheme a track density has been increased to 17 kTPI, equivalent to a level in an optical recording. A flying height is 0.055 m̈m and a longitudinal recording method has been employed. Several new technologies including a narrow‐track composite magnetic head, a low‐noise longitudinal bilayer magnetic medium, high‐sensitive position detection scheme using a semiconductor laser, and accurate positioning mechanics using a dual‐stage actuator have been developed. These technologies are combined into a 3.5‐inch rigid disk drive system. An ultrahigh‐density recording of 2‐GB/in2, which is 10 to 20 times larger compared to a current density, has been confirmed to be possible in combination with a signal processing technology which can cope with a deterioration in the reproduced signal‐to‐noise ratio (SNR).
Diode decoder circuits for ultrahigh‐speed memory
Authors: Ohhata Ken'Ichi , Homma Noriyuki , Kanetani Kazuo , Nambu Hiroaki , Yamaguchi Kunihiko 
Published: July 2007

AbstractDiode decoders are often used in ultrahigh‐speed memory. The AND gate in this type of decoder consists of several diodes and the output voltage of the decoder varies depending on the number of conducting diodes. Although this variation in the output level is an important problem, it has not yet been studied in detail. This paper describes the mechanism of this effect and shows how it affects the performance of the decoder. The parasitic capacitance of the output node, the deviation of the output voltage, and the operating speed are compared for three kinds of diode decoders: a downward diode decoder, an upward diode decoder, and Schottky barrier diode (SBD) decoder, using 0.8‐μm SICOS (sidewall base contact structure) technology. It is shown that the upward diode decoder provides the highest performance. This high performance is demonstrated using the upward diode detector in a 64‐kb RAM.
Use of the faraday effect for frequency stabilization and control of a semiconductor laser
Authors: Ueno Takashi , Rikukawa Hitoshi , Nakazawa Takao , Sato Takashi , Shimba Minoru 
Published: July 2007

AbstractTo date, frequency stabilization methods for semiconductor lasers mainly use the absorption line of an atom or molecule to modulate the frequency of laser light slightly so as to obtain a control signal. As a result, an oscillation bandwidth broadening will appear and the stabilization point will be restrained at the center frequency of the absorption line. This paper reports a frequency stabilization method using a magneto‐optical effect, the Faraday effect of an atomic absorption line, instead of direct modulation of the oscillation frequency. This stabilization method made it possible to control the stabilization point frequency by changing the dc magnetic field. With an Rb absorption line as the frequency reference, the controlled frequency range was about 1.5 GHz, which is wider than the Doppler width of the Rb absorption line at room temperature. The experimental results were consistent with the theoretical analysis.