Book Chapters

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https://hdl.handle.net/20.500.14170/183

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Now showing 1 - 3 of 3
  • Publication
    Impact of notch structures on transfer characteristics of AlGaN/GaN HEMTs: a simulation study
    (Trans Tech Publications Ltd., 2023)
    Muhaimin Haziq
    ;
    Norshamsuri Ali @ Hasim
    ;
    Shaili Falina
    ;
    Hiroshi Kawarada
    ;
    Mohd Syamsul
    Lateral GaN devices, with a substantial critical breakdown field and increased mobility of two-dimensional electron gas (2DEG), are particularly promising for future power applications. Despite low power consumption by design, further improvements are required in numerous areas, including reliability concerns and switching loss, usually contributing to significant power loss. The research objective concerns the impact of different notch structures on the transfer characteristics of GaN-based high-electron-mobility transistor (HEMT) devices. Thirteen simulated models were produced using COMSOL Multiphysics, incorporating the electrical, structural, and piezoelectric effects of the device. From the results, notch-structure devices demonstrated better electrical characteristics than devices using conventional architecture, particularly a model with a double-notch design. Higher transconductance and maximum drain current were among the improvements, benefiting from the notch structure at the barrier layer.
  • Publication
    Micro-power energy harvester using piezoelectric for acoustic sound wave energy harvesting
    (Springer, 2020)
    Haris Fazilah Hassan
    ;
    Rosemizi Abd Rahim
    The advancement of portable electronic devices and the ever-increasing integrated functions which have become a necessity in smartphones, tablets and similar devices have prompted the industry to look for portable power supplies to enhance the lifetime and the usage of portable electronic devices. Therefore, harvesting free energy from the surroundings to provide usable electrical energy could be an interesting solution toward this requirement. In this paper, sound waves energy which is in the form of a pressure wave is investigated to be as a source of free energy which is abundant in our surroundings. The piezoelectric type called PZT 5A bimorph cantilever was introduced as a sound energy harvester during an experimental work. The piezoelectric was tested to extract sound energy produced by the loudspeaker at several predetermined distances from the loudspeaker. The result shows that the maximum voltage of 83 mVpeak was obtained with the sound intensity of 102.6 dB at a resonant frequency of 374 Hz, and the maximum power of 3.445 µW was produced at 1 kΩ of optimal load resistance.
      4  2
  • Publication
    Miniaturized two-section branch-line coupler using open-stub slow-wave structure
    (Springer, 2020)
    Kok Yeow You
    ;
    Jaw Chung Chong
    ;
    Mohd Fareq Abdul Malek
    ;
    Yeng Seng Lee
    ;
    Sehar Mirza
    This study presents the miniaturization of two-section branch microstrip lines coupler using the slow-wave technique. Regular and miniature branch-line couplers operating at 2.4 GHz are designed, fabricated, tested, and compared. Up to 38% reduced size of the miniature coupler is achieved compared to the conventional coupler. The miniaturized coupler is capable of operating from 1.85 to 3.2 GHz with a bandwidth of 1.35 GHz. Overall, the simulation and measurement results demonstrated a good agreement.
      1  7