研究者詳細 - 豊田　啓孝

論文 - 豊田　啓孝

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A Study on Evaluation Board Requirements for Assessing Vulnerability of Cryptographic Modules to Side-Channel Attacks 査読

Kengo Iokibe, Tomonobu Kan, Yoshitaka Toyota

2020 IEEE International Symposium on Electromagnetic Compatibility & Signal/Power Integrity (EMCSI) 2020年7月

Mitigating differential skew by rotating meshed ground for high-density layout in flexible printed circuits 査読

Wang Chenyu, Iokibe Kengo, Toyota Yoshitaka

IEICE Electronics Express 17 ( 10 ) 20200101 - 20200101 2020年5月

担当区分：最終著者,　責任著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人電子情報通信学会

Asymmetry of differential transmission lines over a meshed ground plane causes differential skew, which leads to signal integrity issues. We measured to evaluate how the angle between the differential transmission lines and meshed ground (the rotation angle) affected differential skew. We also investigated the effect of the lines' position on characteristic impedance and the feasibility of high-density layout of the differential transmission lines, including the bend structure. We found that the differential skew and characteristic impedance are not significantly affected by the position of the differential transmission lines and meshed ground when the rotation angle is set to 30°, a relatively small value. Measurements showed that our design is effective.

DOI： 10.1587/elex.17.20200101

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Signal-source estimation from magnetic field image obtained using atomic magnetometer and digital micro-mirror device 査読

Shuji Taue, Yoshitaka Toyota

OPTICAL REVIEW 27 ( 2 ) 258 - 263 2020年4月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：OPTICAL SOC JAPAN

Visualization of an electromagnetic field distribution is helpful for spatial evaluation of field leakage and can aid in solving inverse problems of signal-source estimation. Optical detection is more accurate and less invasive than other methods owing to a low metal content in the sensing probes and signal wires. We have previously reported optical detection of alternating magnetic fields using an alkali-metal atomic magnetometer. In this study, we have proposed a method for imaging the field in a 10 mm diameter area in the sensor head and achieved a resolution below 0.3 mm using a digital micro-mirror device. In this paper, we demonstrate the visualization of an alternating magnetic field at 70 kHz, generated using a Helmholtz coil and a 0.5-mm diameter metal wire attached to the sensor head. Both the uniform field image from the coil and the gradient field image from the wire were clearly observed. The output linearity of the magnetometer was investigated by varying the electric current applied to the coil. In addition, we performed signal-source estimation from the gradient field image. The obtained and calculated distributions were compared to estimate the position of the wire. The estimated wire depth of 1.41 mm was within the range of actual wire depths. This measurement technique has the potential for application in precise position estimation of signal sources with high sensitivity.

DOI： 10.1007/s10043-020-00591-y

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コモンモード放射シミュレーション用電流配分率算出のためのコネクタの簡易モデル構築

豊田啓孝, 金尾奨, 佐田野勝水, 五百旗頭健吾

エレクトロニクス実装学術講演大会講演論文集 34 3B4 - 3 2020年

記述言語：日本語出版者・発行元：一般社団法人エレクトロニクス実装学会

ケーブル-コネクタ間の平衡度不整合によるコモンモード発生、さらに、放射シミュレーションを行うには、コネクタの電流配分率を容易に算出できることが不可欠である。今回、コネクタのSパラメータから電流配分率を算出する簡易モデルを構築したのでこれを報告する。

DOI： 10.11486/ejisso.34.0_3B4-03

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Design of Vialess Open-stub EBG Structure by Using Preference Set-based Design Method 査読

Yoshitaka Toyota, Sho Kanao, Kengo Iokibe

2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE 2019年9月

AC magnetic field imaging by using atomic magnetometer and micro-mirror device 査読

Shuji Taue, Nao Arita, Yoshitaka Toyota

2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE 253 - 256 2019年9月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：IEEE

Visualizing an AC magnetic field distribution is valuable to evaluate spatially as signal or noise components and to estimate locations of signal sources. We propose an optical imaging technique to visualize AC magnetic field distributions. An atomic magnetometer with phase sensitive detections realize optical detections of the AC field with dividing into two axes. A digital micro-mirror device enables us to obtain the field image in 10 mm square area with sub-mm spatial resolution. As a result, bi-directional AC-field images from a fine metal-wire were obtained. The obtained images allow us to evaluate field distributions clearly. This imaging technique has a potential for spatial evaluations of AC field from electrical and electronic devices.

DOI： 10.1109/emceurope.2019.8871985

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Modifying Noise Source Amplitude Modulation Technique to Estimate Magnitude and Phase of Emissions from Individual Integrated Circuits 査読

Kengo Iokibe, Shimpei Yoshino, Yusuke Yano, Yoshitaka Toyota

2019 International Symposium on Electromagnetic Compatibility - EMC EUROPE 2019年9月

A Method for Optimally Designing Snubber Circuits for Buck Converter Circuits to Damp LC Resonance 査読

Yusuke Yano, Naoki Kawata, Kengo Iokibe, Yoshitaka Toyota

IEEE Transactions on Electromagnetic Compatibility 61 ( 4 ) 1217 - 1225 2019年8月

担当区分：最終著者記述言語：英語掲載種別：研究論文（学術雑誌）出版者・発行元：Institute of Electrical and Electronics Engineers (IEEE)

A method for optimally designing RL and RC snubber circuits is presented to reduce the electromagnetic interference caused by parasitic LC resonance. The Q factor of the resonance is used as the design criteria. Optimum snubber parameters are determined analytically and uniquely by using a simplified equivalent circuit of the resonant loop and deriving an analytical formula for the Q factor as a function of the snubber parameters. The optimally designed snubbers can adequately adjust the Q factor to any design target. They can also minimize the increases in the negative effects of the snubbers, i.e., overshoot and power loss. The method was applied to RL and RC snubbers to be added to a synchronous buck converter. The effects of the snubbers were reproduced by simulation program with integrated circuit emphasis ( SPICE) simulation to validate the method from the perspective of resonance damping, overshoot, and power loss. The results showed that the damping effects obtained with the optimized snubbers met the Q factor design targets. They also demonstrate that the parameters are optimum in terms of suppressing overshoot and power loss. These results indicate that the method is suitable for optimizing RL and RC snubbers to damp parasitic LC resonance.

DOI： 10.1109/temc.2018.2841424

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Suppression of Mode Conversion by Improved Shielding Effect of Ethernet Cable Connector Based on Imbalance Factor Matching

Md. Ashraful Islam, Ryota Irishika, Kengo Iokibe, Yoshitaka Toyota

International Conference on Computer, Communication, Chemical, Materials and Electronic Engineering (IC4ME2) 2019年7月

Parameter Identification Based on Measurement and EMI Prediction of Noise-source Equivalent Circuit Model for Power Converters 招待

Yoshitaka Toyota

International Conference on Computer, Communication, Chemical, Materials and Electronic Engineering (IC4ME2) 2019年7月

Randomly Shifted Mesh Position of Meshed Ground for High-Density Mounting in FPCs 査読

Chenyu Wang, Kengo Iokibe, Yoshitaka Toyota

2019 IEEE International Symposium on Electromagnetic Compatibility, Signal and Power Integrity (2019 IEEE EMC+SIPI) 2019年7月

Reduction Mechanism of Differential-Mode Crosstalk between Adjacent Differential Pairs with Periodic Structure 査読

Chenyu Wang, Hiroaki Takeda, Kengo Iokibe, Yoshitaka Toyota

2019 Joint International Symposium on Electromagnetic Compatibility and Asia-Pacific International Symposium on Electromagnetic Compatibility, Sapporo (EMC Sapporo & APEMC 2019) 2019年7月

Suppression of Mode Conversion by Improving Shielding Around Ethernet Connector with Imbalance Matching 査読

Md. Ashraful Islam, Ryota Irishika, Kengo Iokibe, Yoshitaka Toyota

2019 Joint International Symposium on Electromagnetic Compatibility and Asia-Pacific International Symposium on Electromagnetic Compatibility, Sapporo (EMC Sapporo & APEMC 2019) 2019年6月

Improvement of Prediction Accuracy of Noise-source Equivalent-circuit Model Based on Parameter Extraction by Port Voltage/Current Measurement 査読

Taishi Uematsu, Yuhei Osaki, Yusuke Yano, Kengo Iokibe, Yoshitaka Toyota

2019 Joint International Symposium on Electromagnetic Compatibility and Asia-Pacific International Symposium on Electromagnetic Compatibility, Sapporo (EMC Sapporo & APEMC 2019) 2019年6月

Experimental Identification of Relationship between Leakage Trace SNR and Correlation Coefficient in Differential Power Analysis 査読

Yusuke Yano, Toshiaki Teshima, Kengo Iokibe, Yoshitaka Toyota

2019 Joint International Symposium on Electromagnetic Compatibility and Asia-Pacific International Symposium on Electromagnetic Compatibility, Sapporo(EMC Sapporo & APEMC 2019) 2019年6月

ノイズ源振幅変調と相関解析に基づくノイズ源IC毎の電磁妨害波強度推定査読

吉野慎平, 五百旗頭健吾, 矢野佑典, 豊田啓孝

エレクトロニクス実装学会誌 22 ( 3 ) 218 - 225 2019年5月

担当区分：最終著者記述言語：日本語掲載種別：研究論文（学術雑誌）出版者・発行元：一般社団法人エレクトロニクス実装学会

EMI対策および評価コストの削減を目的として，ノイズ源IC毎の放射強度推定法を提案する。この手法はEMI発生要因の1つであるスイッチング電流を振幅変調し，その時の電磁妨害波の時間変化を観測することで得られるノイズ源強度比から各ICの放射強度を推定する。本論文では，プリント回路板に提案手法を適用し，遠方界放射から複数ICによる放射の強度を算出，さらにIC個別に駆動した測定結果と比較し推定精度を評価した。その結果，各ICに起因する放射が同相と見なせる場合に放射強度を高い精度で推定可能であることを示した。

DOI： 10.5104/jiep.22.218

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差動配線とメッシュグラウンドのなす角に着目した差動スキュー低減査読

王晨宇, 五百旗頭健吾, 豊田啓孝

電子情報通信学会論文誌 B J102-B ( 3 ) 228 - 236 2019年3月

Identification of Dominant ICs for Electromagnetic Emission by Using Noise Source Amplitude Modulation and Correlation Analysis

Shimpei Yoshino, Chiaki Ishida, Kengo Iokibe, Yoshitaka Toyota, Yasuyuki Nogami

IEEE International Symposium on Electromagnetic Compatibility 2018-August 439 - 444 2018年10月

掲載種別：研究論文（国際会議プロシーディングス）

To identify semiconductor devices that are dominant noise sources at low cost in order to reduce electromagnetic interference (EMI), we propose a method based on a noise source amplitude modulation technique and correlation analysis (NSM-CA). In this study, we applied the NSM-CA method to a printed circuit board (PCB) with multiple integrated circuits (ICs) and identified ICs dominantly contributing to EM emission. The switching currents produced in three of the ICs were modulated in amplitude with three different modulation signals. The noise source amplitude modulation was implemented in an FPGA, mounted on a PCB, by using three pseudorandom binary sequences (PRBSs) as modulation signals. During the modulations, EM emission was measured at frequencies where the emission exceeded the limit of EMI regulation. The temporal variation in the measured emission was correlated with each of the PRBSs. The ranking of the contributions of the ICs to the emission was determined by means of the resultant correlation coefficients. According to the ranking, the dominant ICs to which a combination of EMI reduction techniques should be primarily applied were identified. Moreover, we applied an EMI reduction technique to the dominant ICs and found a larger reduction in emission than when the technique was applied to low priority ICs.

DOI： 10.1109/EMCEurope.2018.8485011

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A Study of Installation Location and Mechanism to Suppress Power-Bus Resonance Efficiently Using Lossy Resonator Filters

Sho Kanao, Kengo Iokibe, Yoshitaka Toyota

2018 International Symposium on Electromagnetic Compatibility (EMC EUROPE) 2018年8月

Extension of signal-to-noise ratio measurement method to byte-by-byte side-channel attack

Kengo Iokibe, Toshiaki Teshima, Yusuke Yano, Yoshitaka Toyota

2018 IEEE International Symposium on Electromagnetic Compatibility and 2018 IEEE Asia-Pacific Symposium on Electromagnetic Compatibility, EMC/APEMC 2018 745 - 748 2018年6月

記述言語：英語掲載種別：研究論文（国際会議プロシーディングス）出版者・発行元：Institute of Electrical and Electronics Engineers Inc.

Signal-to-noise ratio (SNR) of side-channel traces leaked from cryptographic ICs can be a candidate of system-designer-friendly design index in security evaluation against the side-channel attack (SCA). A method to calculate SNR of side-channel traces from measured side-channel traces was proposed for the scenario of the byte-by-byte attack on AES cryptographic circuits. The proposed method was a simple extension of an SNR calculation method for the brute force attack scenario proposed in a previous study. Measured SNRs according to the methods were validated by comparison with analytical formulas. Results suggested that the proposed method could provide SNRs of side-channel traces accurately.

DOI： 10.1109/ISEMC.2018.8393880

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