IEICE Electronics Express
Online ISSN : 1349-2543
ISSN-L : 1349-2543
Volume 18 , Issue 5
Showing 1-7 articles out of 7 articles from the selected issue
LETTER
  • Haishan Tian, Fangfang Ju, Hongshan Nie, Yuanyu Wu, Qiong Yang, Shuang ...
    Type: LETTER
    Subject area: Circuits and modules for storage
    2021 Volume 18 Issue 5 Pages 20210005
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 05, 2021
    JOURNALS FREE ACCESS

    The airborne sensors with high data rate demand the onboard high-speed storage system due to the limited bandwidth of the downlinks. The NAND Flash and its products are the most common storage medium, and the conventional FAT file system is widely used in the storage systems. However, there has been a problem in recording the live high-speed data stably with this file system. The management time of the FAT file system is relatively long due to the internal overhead which includes the retrieving and updating of the FAT and FDT. The aim of this study is to investigate the technology for the real-time file system. A technology called FPFPA (FAT post- and FDT post- allocation) method is presented to solve this problem. To evaluate the performance of the proposed method, the management time of the file system using our proposed method is tested on the high-speed storage system of an airborne radar. The result indicates that the proposed method achieves our goal successfully in that the management time of the file system is significantly reduced and sufficiently small.

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  • Masataka Motoyama, Ken Umeno
    Type: LETTER
    Subject area: Electromagnetic theory
    2021 Volume 18 Issue 5 Pages 20210011
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 10, 2021
    JOURNALS FREE ACCESS

    This letter aims to demonstrate the concept of wireless power coloring (WPC), i.e., frequency division multiplexing of wireless power transfer (WPT). Currently, to obtain significant received power in WPT, the power is generated from a single transmission source. Herein, we propose a method of transmitting wireless power through more than one (N≧2) multiplexed coloring source. To achieve this, we use power transmitting sources with different resonance frequencies in magnetic resonance-type WPT to selectively send power to a designated receiver.

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  • Kodai Matsuhashi, Koutaro Hachiya, Toshiki Kanamoto, Shinsuke Kashiwaz ...
    Type: LETTER
    Subject area: Devices, circuits and hardware for IoT and biomedical applications
    2021 Volume 18 Issue 5 Pages 20210017
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 10, 2021
    JOURNALS FREE ACCESS

    Wearable technology has been rapidly evolving. Many functions beyond current smartphone capabilities must be realized in wearables that are smaller than smartphones. Heat generation due to power consumption may cause both circuit malfunctions and low-temperature burns. This letter presents thermal design methods to promote heat dissipation of wrist wearables. First, the thermal model to easily obtain each part temperature is described. Next, belt heat dissipation effects are clarified by simulations with the model. The results indicate that each technique using the belt width, thickness, length, covering rubber, or heatsink has a high effect on heat dissipation. In addition, by combining these techniques, temperature rises of the display, bottom of device body, and belt can be reduced by 30.5%, 52.4%, and 52.7%.

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  • Hanxiang Wang, Changchun Chai, Yuqian Liu, Han Wu, Wei Zhang, Fuxing L ...
    Type: LETTER
    Subject area: Electron devices, circuits and modules
    2021 Volume 18 Issue 5 Pages 20210020
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 09, 2021
    JOURNALS FREE ACCESS

    The two-dimensional thermoelectric models of single-junction and triple-junction GaAs solar cells are established respectively utilizing Sentaurus-TCAD, to investigate the damage effects caused by HPMs. Simulation results demonstrate that there are two burnout mechanisms of GaAs solar cells: damage caused by Joule heat accumulation under high electric field, and failure due to temperature surges induced by avalanche breakdown. In addition, fitted empirical formulas also show that burnout caused by Joule heat accumulation at the inflection point of the cathode front surface field occurs when the frequency of injection is above 3GHz, and damage energy decreases as the frequency increases. In contrast, the avalanche multiplication effect in the reverse-biased space charge region near the back-surface field can be triggered when the frequency is below 3GHz, and damage energy rises as the frequency rises. Besides, due to the enhancement of heat dissipation and the drop in avalanche ionization rate, the multi-junction GaAs solar cell becomes more difficult to burn out than the single-junction solar cell under the same HPM interference. Moreover, an equivalent model (based on the carrier mobility distribution when the injected HPMs signal does not reach the burnout threshold) is rebuilt to study the soft damage effect on the performance of GaAs solar cells, as caused by the injection of HPMs.

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  • Pengyu Liu, Wenjie Shi, Tonghui Guo, Guanjing Ren, Sheng Zhang
    Type: LETTER
    Subject area: Integrated circuits
    2021 Volume 18 Issue 5 Pages 20210045
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 12, 2021
    JOURNALS FREE ACCESS

    Miniaturization of DNA fluorescence sequencing is important to reduce costs and promote audiences. Among them, CMOS image sensor (CIS) is an effective method for fluorescence detection. In order to solve the problems of large pixel area and low throughput in CIS chip sequencing technology, we have designed a new CIS pixel structure with special hexagonal topology, reduced floating diffusion (FD) capacitance, improved conversion gain, and applied neighborhood-dark-current-cancellation technology. Simulations using sentaurus and lumerical FDTD software show that the capacitance of FD node is 0.48fF and 0.496fF for different PDs respectively, meaning the whole conversion gain is about 320 uV/e- before the back-end process. The relationship between the sensitivity efficiency of hexagon pixel structure and the edge length of the photodiode (PD) shape and the micro lens (ML) shape was investigated. The optimal design conditions were determined, that is, 1.8 um hexagon PD edge length, or 1.6 um octagon PD edge length, with 2.3 um ML thickness and 2.5 um curvature radius.

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  • Yuito Sawayama, Takayuki Morishita, Kiyotaka Komoku, Nobuyuki Itoh
    Type: LETTER
    Subject area: Integrated circuits
    2021 Volume 18 Issue 5 Pages 20210046
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 19, 2021
    JOURNALS FREE ACCESS

    In this paper, small-area dual-band concurrent LNA with small gain deviation and low NF at a wide frequency range has been studied. Proposed LNA incorporates mutual inductive notch filter matching circuit on the input/output sides to improve gain deviation and NF, to reduce circuit area, and to expand operating frequency range. The measured S11, S22, S21, and NF were -14.2/-10.9, -10.0/-16.5, 10.9/10.3, and 2.64/2.99dB at 1.54/4.38GHz, and gain deviation was 0.6dB between the desired frequencies. Furthermore, the area is 0.47mm2. This LNA was designed by using TSMC-180nm CMOS process.

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  • Caoyu Li, Fei You, Jun Peng, Ce Shen, Songbai He
    Type: LETTER
    Subject area: Microwave and millimeter wave devices, circuits, and modules
    2021 Volume 18 Issue 5 Pages 20210064
    Published: March 10, 2021
    Released: March 10, 2021
    [Advance publication] Released: February 22, 2021
    JOURNALS FREE ACCESS

    A Memory Cross Volterra model for Doherty power amplifiers (PA) with delay mismatch is presented in this letter. During the design process of Doherty power amplifier, gain, efficiency and operation bandwidth are mostly considered. Delay mismatch is difficult to avoid in this kind of dual-path circuit, which reduces the modeling performance of traditional behavioral models. The proposed Memory Cross Volterra Model (MCVM) is derived from the combination of three memory polynomial equations with delay mismatch. Simulation results show that the proposed MCVM has about 10 dB improvement in Normalized Mean Square Error (NMSE) compared to Generalized Memory Polynomial (GMP) with the same model complexity level as GMP. In a measurement experiment, a Doherty PA is tested at 3.45 GHz with 20 MHz LTE signal. Compared with GMP, the proposed MCVM has a maximum 2.5 dB improvement in Adjacent Chanel Power Ratio (ACPR), and the inverse modeling Normalized Mean Square Error (NMSE) is improved from -41.7 to -44.3.

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