Faculty Profiles - TOYOTA Yoshitaka

MISC - TOYOTA Yoshitaka

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C-3-46 Analysis of Interleaver with Double-Cavity Ring-Resonator Structure

Hidayat I.S., Ohnishi M., Ichi-uma S., Toyota Y., Wada O., Koga R.

Proceedings of the Society Conference of IEICE 2001 ( 1 ) 156 - 156 2001.8

Spectrum analysis of amplitude-expanded pulse generated by pillbox-type optical modulator

Ichi-uma Satoru, Hidayat Iip Syarif, Toyota Yoshitaka, Wada Osami, Koga Ryuji

Proceedings of the Society Conference of IEICE 2001 ( 1 ) 115 - 115 2001.8

Power Current Simulation for EMC Design of LSI

TAKAYAMA Keisuke, KINOSHITA Tomohiro, MATSUNAGA Shigeki, WANG Zhi Liang, TOYOTA Yoshitaka, WADA Osami, KOGA Ryuji, FUKUMOTO Yukihiro, SHIBATA Osamu

IEICE technical report. Electromagnetic compatibility 101 ( 178 ) 73 - 78 2001.7

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

High frequency currents flowing from power terminals of an IC/LSI onto power/ground planes of a digital printed circuit board can generate a great amount of electromagnetic noise. A power current model of an IC/LSI for EMI simulation was proposed in our previous studies. This report describes the mechanism and quantitative effect of reducing high frequency currnts on power/ground terminals by embedding a decoupling inductor and/or a bypass capacitor in an IC/LSI package. Furthermore, the above internal decoupling effect on suppressing EMI radiated from the board is verfied in both the simulations and measurements.

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Stable inversion method for a polarized-lidar: analysis and simulation

H Wei, R Koga, K Iokibe, O Wada, Y Toyota

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 18 ( 2 ) 392 - 398 2001.2

Language：English Publisher：OPTICAL SOC AMER

A new inversion inhomogeneous atmosphere (IA) method that is more stable than Fernald's method for two-component (molecule and aerosol) scattering analysis of polarized Mie lidar signals is proposed and examined. The backscattering coefficient and the extinction-to-backscattering ratio (EBR) can be calculated for specified regions at which the depolarization ratio is less than that of molecule without further assumptions. The inversion procedure can be extended to both inward stepwise and outward stepwise integration algorithms. Simulation results indicate that a higher precision was achieved with the IA method than with Fernald's method in terms of error and random noise in estimating boundary value and EBR. Experimental results were also better with the IA method than with Fernald's method. (C) 2001 Optical Society of America OCIS codes: 280.0280, 280.3640, 280.1100.

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Numerical analysis of amplitude-expanded pulse generation in pillbox-type optical modulator

TOYOTA Yoshitaka, WADA Osami, KOGA Ryuji

Technical report of IEICE. OPE 100 ( 590 ) 1 - 6 2001.1

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

We propose an optical modulator which is composed of thin disk pillbox-type resonators, coupling waveguides, and electrodes. Considering proton exchanged LiNbO_3 as a material, frequency characterisitcs of a pillbox-type optical modulator is numerically analyzed with scattering matrices. Amplitude-expanded pulse generation for modulation signals, such as sinusoidal wave and triangle pulse, is numerically calculated by changing modulation frequency. As a result, the mechanism of the amplitude-expanded pulse generation is clarified, and it is found that the amplitude of output pulse in theory is 9 times as large as the one of CW input.

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Depolarization properties of Asian dust (Kosa) measured in 1998-2000 at Okayama, Japan

H Wei, R Koga, K Iokibe, O Wada, Y Toyota, N Kagawa

LIDAR REMOTE SENSING FOR INDUSTRY AND ENVIRONMENT MONITORING 4153 559 - 566 2001

Language：English Publisher：SPIE-INT SOC OPTICAL ENGINEERING

A Mie lidar system was built at Okayama University in 1998. The system is featured by the ability of discriminating depolarization of received signals with a spatial resolution of 15m. Examinations were conducted on the received range-normalized signal and the depolarization ratio from Asian dust. Intense Asian dust occurred in springs of 1998-2000.
Vertical distribution of Asian dust was found to be inhomogeneous contrary to the homogeneity assumption employed in preceding works. Multiple scattering in the layers of Asian dust also observed. Complicated structure of Asian dust wrapped by liquid or water droplets were also conjectured from the sudden changes of depolarization ratio in Asian dust layers.

DOI： 10.1117/12.417092

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Power current model of LSI and parameter identification for EMI simulation of digital PCBs

Y Fukumoto, T Matsuishi, T Kinoshita, O Wada, Y Toyota, R Koga

2001 IEEE EMC INTERNATIONAL SYMPOSIUM, VOLS 1 AND 2 1185 - 1190 2001

Language：English Publisher：IEEE

A power current model of LSIs for EMI simulation of digital printed circuit boards, and a parameter identification method based on the model are presented. The model consists of equivalent internal impedance and an equivalent internal current source. The equivalent internal impedance is obtained by measuring the impedance between the power and ground terminal of an LSI by means of an impedance analyzer, and an equivalent internal source is obtained from the measured current through the power terminal under the conditions of known external impedance. Furthermore, it is shown that simulation results generated using this model have good agreement with the results of measurements made under a range of external impedances.

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Reduction of Q-factor of resonance in power/ground planes of multilayer PCBs by using resistive metal films

Zhi Liang Wang, Osami Wada, Yoshitaka Toyota, Ryuji Koga

Trans. Inst. Electr. Eng. Jpn. A 2001

Local Decoupling Effects of Decoupling Capacitors on a Multilayer PCB : Fast Analysis by a Closed-Form Expression

WADA Osami, WANG Zhi Liang, TOYOTA Yoshitaka, KOGA Ryuji

EMCJ 100 ( 510 ) 85 - 90 2000.12

Language：English Publisher：The Institute of Electronics, Information and Communication Engineers

Decoupling capacitors are often utilized to mitigate ground bounce and EMI problems in a printed circuit board (PCB). In this report, a new modeling approach to investigate the decoupling is proposed, based on a closed-form expression for the Z-matrix of the power/ground planes in a multi-layer PCB together with the lumped circuit models of decoupling capacitors. The calculated results show that the input impedance which determines the excitation efficiency of the power/ground resonances is locally decreased by a decoupling capacitor closely spaced to the excitation port. The local decoupling effect is quantitatiely presented as a function of the spacing between the excitation port and the local decoupling capacitor.

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An Improved Closed-Form Expression for Accurate and Rapid Calculation of Power/Ground Plane Impedance in Multilayer PCBs

WANG Zhi Liang, WADA Osami, TOYOTA Yoshitaka, KOGA Ryuji

2000 ( 65 ) 17 - 23 2000.10

Parameter Identification for a power current model of LSI

FUKUMOTO Yukihiro, MATSUISHI Takuya, TOYOTA Yoshitaka, WADA Osami, KOGA Ryuji

EMCJ 100 ( 207 ) 49 - 54 2000.7

Language：Japanese Publisher：The Institute of Electronics, Information and Communication Engineers

A power terminal model, which represents high frequency current on power terminal of IC/LSI, in necessary to perform power bus noise simulations of digital printed circuit boards. In this report, the model, which has equivalent internal impedance and an equivalent internal current source, is proposed. The model can express high frequency current which is affected by the impedance of bypass capacitors and power bus traces on printed circuit board. Parameters in the equivalent internal impedance are given by the impedance analyzer, and the equivalent internal current source can be calculated by measured high frequency current which is obtained under certain external impedance. Furthermore, it is shown that outputs of the model give good agreement with experimental results under various conditions of external impedance.

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Reducing Q-factors of Resonances in Power/Ground Planes of Multilayer PCBs by Using Resistive Metallic Layers

Zhi Liang Wang, Osami Wada, Yoshitaka Toyota, Ryuji Koga

Proceedings of the 2000 Japan-China Joint Meeting on Optical Fiber Science and Electromagnetic Theory (OFSET) 2000 2000

Observation of Kosa with Mie Lidar at Okayama in the Spring of 2000

Ryuji Koga, Kengo Iokibe, He Wei, Osami Wada, Yoshitaka Toyota, Naoki Kagawa

The Proceedings of Asian Lidar Observation Network Conference 2000 2000

Power Current Model of Digital IC with Internal Impedance for Power Decoupling Simulation

Osami Wada, Yasuo Takahata, Yoshitaka Toyota, Ryuji Koga, Takuya Miyashita, Yukihiro Fukumoto

4th European Symposium on Electromagnetic Compatibility Proceedings 2000

Depolarization properties of Asian dust (KOSA) measured hyLIDAR in Okayama in the spring of 1998

Wei He, Koga Ryuji, Iokibe Kengo, Wada Osami, Toyota Yoshitaka

Memoirs of the Faculty of Engineering, Okayama University 34 ( 1 ) 27 - 37 2000

Power decoupling circuit for modeling and measurement of EMC characteristics of IC/LSI

R Koga, O Wada, Y Toyota, T Miyashita, Y Fukumoto, A Namba, Y Takahata, N Kagawa

ASIA-PACIFIC CONFERENCE ON ENVIRONMENTAL ELECTROMAGNETICS: CEEM'2000, PROCEEDINGS 444 - 448 2000

Amplitude-expanded pulse generated by pillbox-type optical modulator

SUGA Kunihiro, SHIGE Hideki, TOYOTA Yoshitaka, WADA Osami, KOGA Ryuji

Proceedings of the IEICE General Conference 311 - 311 1999

Yield Measurement of Secondary Electrons Emitted from Silicon Dioxide Film in Negative-Ion Bombardment

Toyota Yoshitaka, Tsuji Hiroshi, Gotoh Yasuhito, Ishikawa Junzo

Jpn J Appl Phys 35 ( 9 ) 4785 - 4788 1996.9

Language：English Publisher：INSTITUTE OF PURE AND APPLIED PHYSICS

The yield of secondary electrons emitted from insulating materials subjected to negative-ion bombardment was studied. In general, such measurements for insulating materials are difficult because surface charging due to ion implantation makes the apparent yield unity. We used silicon dioxide (SiO2) film and a small ion current for the yield measurements. As a result, charge compensation due to the leakage current minimized the surface charging and the true yield was obtained. The experimental results showed that secondary electrons emitted due to negative-ion bombardment consist of electrons due to both kinetic emission and detachment from negative ions. In addition, it was found that the yield depends on the ion species. It was concluded that the same tendencies as those for negative-ion-implanted conductive materials are observed.

DOI： 10.1143/JJAP.35.4785

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Fundamental study on powder-scattering in positive- and negative-ion implantation into powder materials

Hiroshi Tsuji, Junzo Ishikawa, Hajime Itoh, Yoshitaka Toyota, Yasuhito Gotoh

Applied Surface Science 100-101 342 - 346 1996

Language：English Publisher：Elsevier

The scattering of powder particles is caused by charging in the ion implantation of positive ions into dielectric powders without a charge compensation, this makes dose control difficult. We have studied the particle-scattering phenomenon in ion implantation into spherical powders both theoretically and experimentally. Taking into account Coulomb force, Van der Waals force and a gravity working on a sphere, the force balance equation was driven to give the threshold charging voltage above which the charged sphere begins to be scattered. In positive-argon-ion implantation into three oxide powders at an average size of 5, 115 and 425 μm, particle-scattering was observed above each ion-acceleration voltage (i.e., charging voltage) of 6.5, 1.0 and 2.7 kV, respectively. These voltages were in good agreement with the predicted threshold charging voltages. Conversely, in the negative-carbon-ion implantation, on the contrary, there was no scattering for all samples even at an ion acceleration voltage of 20 kV. The negative-ion implantation technique was found to be a non-scattering implantation method for powders.

DOI： 10.1016/0169-4332(96)00238-3

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Charging phenomenon of insulators in negative-ion implantation

Yoshitaka Toyota, Hiroshi Tsuji, Shoji Nagumo, Yasuhito Gotoh, Junzo Ishikawa

Applied Surface Science 100-101 360 - 364 1996

Language：English Publisher：Elsevier

The energy distribution of secondary electrons emitted from an insulator during negative-ion implantation was measured. According to secondary-electron-energy analysis, the charging voltage of insulator was estimated from the measured energy distribution. The experimental results in negative-carbon-ion implantation showed that the charging voltages of a quartz glass plate and a photoresist film on silicon substrate are several negative volts in the energy range from 5 to 35 keV and decrease gradually with increasing ion energy. The low negative charging voltage of insulator and the most probable energy of the secondary-electron energy distribution during negative-ion implantation are discussed using a charging model based on an electric double layer.

DOI： 10.1016/0169-4332(96)00242-5

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