Takamaro Kikkawa

Hiroshima University, Hirosima, Hiroshima, Japan

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Publications (255)216.75 Total impact

  • Xia Xiao · Haiyang Qi · Ye Tao · Takamaro Kikkawa
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    ABSTRACT: The cohesive zone model being increasingly used in discrete fracture processes simulation is adopted to study the interfacial adhesion property of low dielectric constant film deposited on the silicon substrate in this work. The two parameters, maximum normal traction and normal interface characteristic length in cohesive zone model, are taken into account to calculate the theoretical surface acoustic wave dispersion curves. Broadband surface acoustic wave signals with effective frequency up to 200 MHz are generated by short pulse ultraviolet laser source and detected by a piezoelectric transducer. The interfacial adhesion properties of dense and porous films determined accurately by matching the experimental dispersion curves with the calculated theoretical dispersion curves are 10.7 PPa/m and 2.8 PPa/m, respectively. The results show that the adhesion quality of dense low dielectric constant film is better than that of the porous. The study exhibits that the adhesion properties determined by improved laser-generated surface acoustic wave technique have the same trends with the test results of the nanoscratch technique, which indicates that the surface acoustic wave technique with cohesive zone model is a promising and nondestructive method for determining interfacial adhesion properties between low dielectric constant film and substrate.
    No preview · Article · Dec 2015 · Applied Surface Science
  • Qinwei Li · Xia Xiao · Liang Wang · Hang Song · Hayato Kono · Peifang Liu · Hong Lu · Takamaro Kikkawa
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    ABSTRACT: A direct extraction method of tumor response based on ensemble empirical mode decomposition (EEMD) is proposed for early breast cancer detection by ultra-wide band (UWB) microwave imaging. With this approach, the image reconstruction for the tumor detection can be realized with only extracted signals from as-detected waveforms. The calibration process executed in the previous research for obtaining reference waveforms which stand for signals detected from the tumor-free model is not required. The correctness of the method is testified by successfully detecting a 4 mm tumor located inside the glandular region in one breast model and by the model located at the interface between the gland and the fat, respectively. The reliability of the method is checked by distinguishing a tumor buried in the glandular tissue whose dielectric constant is 35. The feasibility of the method is confirmed by showing the correct tumor information in both simulation results and experimental results for the realistic 3-D printed breast phantom.
    No preview · Article · Nov 2015 · IEEE Transactions on Biomedical Circuits and Systems
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    ABSTRACT: There is no abstract available for this article.
    No preview · Article · Jul 2015 · Applied Physics Letters
  • A. Azhari · S. Takumi · S. Kenta · T. Kikkawa
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    ABSTRACT: A DC-17 GHz single pole eight throw (SP8T) switching matrix has been developed on standard 65 nm CMOS process for the first time for impulse radar communication. The measured input and output matching bandwidth are 0-17 GHz where both the input and output return losses are greater than 10 dB. Measured average insertion loss from Tx port to different output ports are 3.6 dB, 6 dB and 10 dB at 3 GHz, 10 GHz and 17 GHz, respectively, with 1.2 mW power consumption. The switch is implemented on printed circuit board with flip chip mounting. A 0-20 GHz matching bandwidth was obtained using quarter wavelength microstripline and a 0.1mm thickness Magatron 6 board. The time domain wideband characteristics of the switch was tested with 8 GHz Gaussian monocycle pulse (GMP).
    No preview · Article · Mar 2015
  • Source
    Dan Zhao · Yi Wang · Hongyi Wu · Takamaro Kikkawa
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    ABSTRACT: Modern embedded SoC design uses a rapidly increasing number of processing units for ubiquitous computing, forming the so called embedded many-core SoCs (McSoC). Such McSoC devices allow superior performance gains while side-stepping the power and heat dissipation limitations of clock frequency scaling. The main advantage lies in the exploitation of parallelism, distributively and massively. Consequently, the on-chip communication fabric becomes the performance determinant. To bridge the widening gap between computation requirements and communication efficiency faced by gigascale McSoCs in the upcoming billion-transistor era, a new on-chip communication system, dubbed Wireless Network-on-Chip (WiNoC), has been proposed by using the recently developed RF interconnect technology. With the high data-rate, low power and ultra-short range interconnection provided by UWB technology, the WiNoC design paradigm calls for effective solutions to overhaul the on-chip communication infrastructure of gigascale McSoCs.
    Preview · Article · Mar 2015
  • T. Kikkawa · A. Toya · X. Xiao
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    ABSTRACT: CMOS equivalent-time sampling circuits for impulse-radio ultra-wideband (IR-UWB) breast cancer detection system was developed. The minimum phase resolution of 9.77 ps and the sampling rate of 102.4 GS/s were achieved for Gaussian monocycle pulses (GMP) with the pulse width of 210 ps. The input analog GMP was converted to digital data by use of a 4-bit analog-to-digital circuit. Target phantom images were reconstructed by confocal imaging algorithm.
    No preview · Article · Jan 2015
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    ABSTRACT: An ultrawideband (UWB) radar-based breast cancer detection system, which is composed of complementary metal–oxide–semiconductor integrated circuits, is presented. This system includes Gaussian monocycle pulse (GMP) generation circuits, switching (SW) matrix circuits, equivalent-time sampling circuits, and a compact UWB antenna array. During the detection process, the GMP signal with the center frequency of 6 GHz is first generated and transmitted with a repetition frequency of 100 MHz. The GMP signal is sent to a selected transmitter antenna by the SW matrix module, and the reflected signal is captured by the receiver antennas. Next, the high-speed equivalent-time sampling circuits are employed to retrieve the reflected GMP signal. A confocal algorithm is used to reconstruct the breast image. The total size for the prototype module is $45~textrm {cm} times 30~textrm {cm} times 14.5$ cm in length, width, and height, respectively, which is dramatically smaller than the conventional detection systems. Using our proposed system, we demonstrate a successful detection of 1-cm cancer target in the breast phantom.
    No preview · Article · Jan 2015
  • Afreen Azhari · Sugitani Takumi · Sogo Kenta · Takamaro Kikkawa · Xia Xiao
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    ABSTRACT: A new single pole eight throw (SP8T) CMOS switching matrix has been developed to replace conventional large mechanical switches, for portable ultra wideband (UWB) breast cancer imaging system. The SP8T switch has an minimum input and output matching bandwidth of 0-17 GHz with an average insertion loss of 3 to 10 dB from 2 to 17 GHz and power consumption of 1.2 mW. By utilizing two of these switching matrices, implemented on printed circuit boards, it has been possible to detect an aluminum target of 10 mm × 10mm at a depth of 20 mm, in a 16 antenna array breast cancer detection system. An 8 GHz center frequency Gaussian monocycle pulse was transmitted through the whole system.
    No preview · Article · Dec 2014
  • Y. Seo · K. Sogo · A. Toya · T. Sugitani · A. Azhari · X. Xiao · T. Kikkawa
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    ABSTRACT: CMOS 102.4 GS/s equivalent time sampling (ETS) circuits with a track and hold, phase-locked loop and analog to digital converter was developed for radar-based breast cancer detection. The track and hold circuits of the ETS covered the bandwidth of 2.9-13.9 GHz by use of a 1.27 nH series inductor to compensate parasitic capacitances. The pulse width and the bandwidth of the input Gaussian monocycle pulse (GMP) were 107 ps and 4.45-15.8 GHz, respectively. The received GMP waveforms by 4×4 antenna array were converted to 4-bit digital codes. A three dimensional confocal imaging of a 20 × 20 mm2 target in a homogeneous breast phantom was demonstrated.
    No preview · Conference Paper · Oct 2014
  • Takumi Sugitani · Kenji Hashimoto · Yuji Seo · H. Kono · Takamaro Kikkawa
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    ABSTRACT: A three dimensional imaging system based on time domain reflectometry (TDR) was developed by use of impulse-radio ultrawide-band (IR-UWB) complementary metal oxide semiconductor integrated circuits (CMOS-IC) with a planar antenna array for a breast cancer detection. A 4×4 planar UWB antenna array having the size of 62 mm × 70.4 mm was developed. Gaussian monocycle pulses (GMP) having the pulse width of 145 ps and the bandwidth of 10 GHz were digitally generated by 65 nm logic-CMOS transmitter and the received signal was converted to digital data by an equivalent time sampling CMOS-IC at the sampling rate of 100 GS/s.
    No preview · Conference Paper · Sep 2014
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    ABSTRACT: High-performance low-temperature poly-Si thin film transistor (LTPS-TFT) with one-dimensionally elongated long crystal grains have been developed. In the LTPS TFTs, the carrier mobility is enhanced, however the off-leakage current also increase. This is because, grain boundary become longer, and bridge the distance between source and drain, and the grain boundary bridge become a current-leakage path. In this paper, we suggest a novel ozone radical treatment for reducing the off-leakage current.
    No preview · Conference Paper · Jul 2014
  • Shinichi Kubota · Akihiro Toya · Takumi Sugitani · Takamaro Kikkawa
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    ABSTRACT: Interchip data transmission was demonstrated using impulse radio ultrawideband complementary metal-oxide–semiconductor (CMOS) transmitter integrate circuits withon-chip dipole antennas. A differential pseudorandom binary sequence of (2^{7}) data of Gaussian monocycle pulse (GMP) was formed by 65-nm CMOS logic circuits using up- and down-pulses with certain gate delays. The CMOS transmitter generated 5-Gb/s GMP with the center frequency of 10 GHz. To improve transmission gains, an interposer with the high dielectric constant ( (varepsilon _{textrm r} =38)) and optimized thickness was inserted under the CMOS chips as a dielectric slab waveguide. 2-Gb/s GMP signals were transmitted and received in the distance of 10 mm by use of the CMOS on-chip antennas and the high- (kappa ) interposer.
    No preview · Article · Jul 2014 · IEEE Transactions on Components, Packaging, and Manufacturing Technology
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    ABSTRACT: The variability in measurements of complex permittivities of tumor tissues between multiple samples could be attributed to the volume fraction of cancer cells in the excised tumor tissue. By the use of a digital photomicrograph image and hematoxylin-eosin staining, it was found that the malignant tumor tissue was not fully occupied by the cancer cells, but the cells were distributed locally in the stroma cells depending on the growth of cancer. The results showed that the volume fraction of cancer cells in the tumor tissue had a correlation to the measured conductivity and dielectric constant in the frequency range from 1 GHz to 6 GHz. It introduces a method to understand and gauge variability in measurements between different tumors.
    No preview · Article · Jun 2014 · Applied Physics Letters
  • Ioan E. Lager · Adrianus T. de Hoop · Takamaro Kikkawa
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    ABSTRACT: The amenability of some model pulses for being employed in the time-domain (TD) design of ultra-wideband (UWB) wireless signal transfer systems is analyzed. The mandatory feature to this end is their causality. Furthermore, a rectangular spectral diagram is desirable for meeting certain practical requirements, such as conformity to international spectrum regulations. The study highlights the favorable properties of the power exponential family of pulses. Moreover, the power exponential modulated sinc-cosine function is shown to combine causality and a spectral content that approximates well the desired rectangular spectral diagram. These features recommend these pulses as excitations for TD (software) models to be employed in the design of UWB wireless systems.
    No preview · Conference Paper · Apr 2014
  • T. Sugitani · S. Kubota · X. Xiao · H. Kono · T. Kikkawa
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    ABSTRACT: Spatial resolution of 4×4 planar ultra-wideband (UWB) antenna array was investigated for a confocal imaging system using Gaussian monocycle pulses. Two separate breast tumor phantoms having 5×5×5 mm3 embedded at the depth of 22 mm with the separation distance of 8 mm were resolved by use of 4×4 array antennas with 6 mm spacing due to the fact that the frequency characteristics of the antenna was improved in the frequency range from 6 to 10 GHz.
    No preview · Conference Paper · Apr 2014
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    ABSTRACT: A time-domain reflectometry breast cancer detection system was developed, which was composed of a Gaussian monocycle pulse (GMP) transmitter circuit fabricated by complementary metal oxide semiconductor (CMOS) 65 nm technology and an ultra wide-band (UWB) planar slot antenna array. The center frequency and bandwidth of the antenna were 6 and 9.2 GHz, respectively. The GMP train having the pulse width of 160 ps was generated by the 65 nm CMOS logic circuit with a core area of 0.0017 mm2 and was emitted by the 4 × 4 planar slot antenna array. The fabricated planar 4 × 4 antenna array with the matching layer could resolve the two separate 5 × 5 × 5 mm3 breast tumor phantoms, which were located at the depth of 22 mm with the spacing of 8 mm.
    No preview · Article · Mar 2014 · Japanese Journal of Applied Physics
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    ABSTRACT: In this research, a partial amorphization is introduced to form a Nickel suicide ohmic contact for a 4H-SiC bottom electrode. In a conventional Nickel suicide electrode, a carbon agglomeration at the silicide/SiC interface occurs, and constant resistance between Ni silicide and SiC substrate becomes larger. To reduce the contact resistance, a partial amorphization of the surface of SiC substrate was introduced. By this partial amorphization, the space position of the carbon agglomeration is controlled, and contact resistance can be reduced. As a result, with an amorphous 100 nm line pattern, a reliable contact resistance of 1.9x10(-3) Omega cm(2) is realized.
    No preview · Conference Paper · Jan 2014
  • Li Xu · Xia Xiao · Takamaro Kikkawa
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    ABSTRACT: Ultra-wide band (UWB) microwave imaging is a promising method for the breast cancer detection based on the large contrast of electric parameters between the malignant tumor and its surrounded normal organisms. In this paper, a two-dimensional model of the breast organisms is numerically carried by the finite difference time domain (FDTD) method. The dispersion characteristics of the breast media are taken into account by single pole Debye model to approach the actual properties of the breast organism. In this method, a tumor is assumed in the model with two cases. The standard Capon beamforming (SCB) and doubly constrained robust Capon beamforming (DCRCB) algorithm performed to reconstruct the image is described in detail. The tumor can be detected and localized using the proposed algorithm and the result demonstrates a good stability of DCRCB algorithm.
    No preview · Article · Jan 2014 · Journal of Circuits System and Computers
  • Seiichi Aritome · Takamaro Kikkawa
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    ABSTRACT: This paper describes scaling limitations and challenges of Self-Aligned STI cell (SA-STI cell) over 2X–0X nm generations for NAND flash memories. The scaling challenges are categorized to (1) narrow Read Window Margin (RWM) problem, (2) structural challenge, and (3) high field (5–10 MV/cm) problem. First, (1) the narrow RWM is investigated by extrapolating physical phenomena of FG–FG coupling interference, Electron Injection Spread (EIS), Back Pattern Dependence (BPD), and Random Telegraph Noise (RTN). The RWM is degraded not only by increasing programmed Vt distribution width, but also by increasing Vt of erase state mainly due to large FG–FG coupling interference. However, RWM is still positive in 1Z nm (10 nm) generation with 60% reduction of FG–FG coupling by air-gap process. For (2) structural challenge, the Control Gate (CG) fabrication margin between Floating Gates (FGs) is becoming much severer beyond 1X nm generation. Very narrow 5 nm FG width/space has to be controlled. For (3) high field problem, high field between CGs (word lines; WLs) is critical during program. By using WL air-gap, high field problem can be mitigated, and 1Y/1Z nm generation seems to be realized. Therefore, the SA-STI cell is expected to be able to scale down to 1Z nm (10 nm) generation, with the air gap of 60% reduced FG–FG coupling interference and an accurate control of FG/CG formation process.
    No preview · Article · Apr 2013 · Solid-State Electronics
  • Akihiro Toya · Kenta Sogo · Nobuo Sasaki · Takamaro Kikkawa
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    ABSTRACT: For application to an impulse-radio ultra-wideband (IR-UWB) portable breast cancer detection system, a 102.4 GS/s sampling circuit is developed. The high sampling rate is realized by an equivalent-time sampling technique and a low-power multi-clock generation circuit using a phase interpolator. The phase interpolator achieved a minimum phase resolution 9.8 ps. Using the sampling circuit, a tumor phantom buried by a breast phantom was detected. (C) 2013 The Japan Society of Applied Physics
    No preview · Article · Apr 2013 · Japanese Journal of Applied Physics

Publication Stats

2k Citations
216.75 Total Impact Points

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  • 1998-2015
    • Hiroshima University
      • Research Institute for Nanodevices and Bio Systems
      Hirosima, Hiroshima, Japan
  • 2013
    • Gunma National College of Technology
      Maebashi, Gunma, Japan
  • 2001-2008
    • National Institute of Advanced Industrial Science and Technology
      Tsukuba, Ibaraki, Japan
  • 2007
    • Tianjin University
      • Department of Electronic Information Engineering
      T’ien-ching-shih, Tianjin Shi, China
  • 2006-2007
    • The Electrochemical Society
      Society Hill, New Jersey, United States
  • 2005
    • Bangladesh University of Engineering and Technology
      • Department of Electrical and Electronic Engineering
      Mujib City, Dhaka, Bangladesh
  • 2004
    • Tsukuba Memorial Hospital
      Tsukuba, Ibaraki, Japan
  • 1989-1997
    • NEC Corporation
      Edo, Tōkyō, Japan