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Sub-ppm acetone gas sensing properties of free-standing ZnO nanorods
摘要： In this paper, ZnO nanorods were synthesized by low cost and simple wet chemical method and used as a highly sensitive acetone gas sensor with detection limit as low as 25 ppb which makes the sensor a promising choice for various applications. The fabricated sensor showed a response value of 1.75 towards 25 ppb acetone at optimum working temperature of 320 °C with a response time of 30s. However, the sensor showed response value of 60 towards 50 ppm acetone with a response time of 15 s. The grown ZnO nanorods were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD) for morphology and crystallinity characterization. According to the SEM images, freestanding nanorods with mean diameter of 80 nm and mean length greater than 1.5um were obtained with highly preferential c-axis orientation.
关键词： Sub-ppm sensing,Gas sensor,Acetone,ZnO Nanorods,Hydrothermal
更新于2025-09-23 15:22:29
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Toward the energy efficiency of multi-pulse PPM signalling for optical communication
摘要： To improve information throughput conventional single-pulse M-ary pulse-position-modulation (PPM) scheme, multi-pulse PPM has been proposed on the optical intensity-modulated and direct-detection channel. Although the multi-pulse M-ary PPM scheme significantly enhances throughput performance, nevertheless, the symbol error rate (SER) increases due to the loss of orthogonality between different pairs of symbols. In this study, the authors first derive the SER performance of general L pulses M-ary PPM scheme under Poisson channel statistic. Moreover, as the green radio is essential in future network, energy efficiency becomes the major concern. Hence, they evaluate L pulses M-ary PPM scheme by the number of reliable bits transmitted per joule of energy consumed. They analyse the trade-off between throughput and power consumption.
关键词： optical communication,symbol error rate,Poisson channel,energy efficiency,multi-pulse PPM
更新于2025-09-23 15:21:01
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Comparative study of photoluminescence of single and mixed phase ZrTiO4 prepared by solution combustion and polymeric precursor method
摘要： This work aims to study synthesis methods and photoluminescence properties of ZrTiO4. Wet chemical routes used for synthesis are solution combustion method and polymeric precursor method. Urea and glycine are two different fuels used in solution combustion synthesis. Scanning Electron Microscope studies con?rms that morphology of the nanoparticles depends on synthesis method. Photoluminescent property depends on the phase of the material, rather than the method of synthesis. Characterization such as X-ray diffraction, SEM, Re?ectance and Photoluminescence studies prove the role of synthesis methods on the properties of the ZrTiO4. Both upconversion and down conversion luminescence have been achieved by synthesizing ZrTiO4 from solution combustion method using urea as fuel, where ZrTiO4 exists in mixed phase.
关键词： Polymeric precursor method, (PPM),Photoluminescence,Single phase,Mixed phase,ZrTiO4,Solution combustion method, (SCS)
更新于2025-09-09 09:28:46
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[IEEE 2018 48th European Microwave Conference (EuMC) - Madrid, Spain (2018.9.23-2018.9.27)] 2018 48th European Microwave Conference (EuMC) - Spurious Mode Suppression in the Design of GCPW Submillimeter-wave Power Amplifiers
摘要： This work investigates the problem of spurious mode propagation in a grounded coplanar waveguide (GCPW) frequencies between 200 GHz and 335 GHz. environment at Design strategies focused on minimizing undesired effects are explored through full-wave electromagnetic (EM) analysis and experimental results from different test structures. It is shown that a λ/13 distance between via-holes should be chosen to avoid unwanted resonances at these high frequencies. The critical role of via-holes is also demonstrated through the experimental comparison of two power splitters. Finally, the need of closed RF pads to avoid any propagation of parasitic modes is experimentally shown in an application example of a power ampli?er (PA) cell based on a 35 nm GaAs metamorphic high electron mobility transistor (mHEMT) technology. The PA cell with closed pads achieves a 0.5 dB bandwidth of 28 % with small-signal gain levels larger than 5.2 dB.
关键词： parallel-plate mode (PPM),via-holes,grounded coplanar waveguide (GCPW),Dolph-Chebyshev divider,metamorphic high electron mobility transistor (mHEMT)
更新于2025-09-04 15:30:14
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[IEEE 2016 IEEE International Symposium on Circuits and Systems (ISCAS) - Montréal, QC, Canada (2016.5.22-2016.5.25)] 2016 IEEE International Symposium on Circuits and Systems (ISCAS) - A 800-Mb/s 0.89-pJ/b reference-less optical receiver with pulse-position-modulation scheme
摘要： A 800-Mb/s optical receiver based on pulse-position-modulation (PPM) scheme is presented. The proposed PPM receiver can recover the clock without any help of a reference clock or a forwarded clock. As a result, the number of wire and pin count is minimized. Moreover, the proposed receiver employs optical front-end circuits for fiber-optic communications which is optimized for low-power operation. The clock and data recovery (CDR) circuit is implemented with only a PLL and a sampling flip-flop to minimize the power consumption of the proposed receiver. A prototype chip is fabricated in 65-nm CMOS technology and dissipates 711 μW at 800-Mb/s data rate, achieving the power efficiency of 0.89 pJ/b. The measured jitter tracking bandwidth of the proposed receiver is about 10 MHz and the receiver sensitivity is measured to be -9.7 dBm for the BER of 10-12.
关键词： low-power,pulse position modulation (PPM),Clock and data recovery (CDR),optical front-end,reference-less receiver
更新于2025-09-04 15:30:14
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[IEEE 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - Atlanta, GA, USA (2018.10.31-2018.11.2)] 2018 IEEE 6th Workshop on Wide Bandgap Power Devices and Applications (WiPDA) - High Voltage GaN Switch Reliability FIT rates and PPM reliability based on standards from: Joint Electron Device Engineering Council (JEDEC), Automotive Electronics Council (AEC) and German Electrical and Electronic Manufacturers' Association (ZVEI)
摘要： Adoption of any semiconductor technology by the power conversion market requires the understanding of fundamental failure modes, acceleration factors and reliability statistics. This study shows how GaN products from Transphorm can meet this challenge, especially in the critical High Voltage Off State (HVOS) reliability stress test. The anticipated failure rate during a product’s first 10 to 20 years of use is of particular interest as it has direct impact on warranty costs. This market requirement can be addressed by testing to failure statistically significant samples of devices, and analyzing the data with appropriate models. The methods developed for measuring GaN reliability on large samples will be discussed, which are wholly based on existing industrial and automotive standards. The resulting data can be used to supplement qualification testing results when the failure modes and acceleration factors are well understood.
关键词： GaN,FIT,PPM,HEMT,acceleration factor,power electronics,reliability
更新于2025-09-04 15:30:14