共查询到20条相似文献,搜索用时 15 毫秒
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The high power light emitting diodes(LEDs) based on InGaN and AlGaInP individually are tested on line at temperatures from -30 to 100℃.The data are fitted to measure the relationship between temperature and the properties of forward voltage,relative light intensity,wavelength,and spectral bandwidth of two different kinds of LEDs.Why these properties changed and how these changes reflected on applications are also analyzed and compared with each other.The results show that temperature has a great influence on the performance and application of power LEDs.For applications at low temperature,the forward voltage rising and the peak wavelength blue-shifting must be considered;and at high temperature,the relative light intensity decreasing and the peak wavelength red-shifting must be considered. 相似文献
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L. Shen R. Coffie D. Buttari S. Heikman A. Chakraborty A. Chini S. Keller S. P. Denbaars U. K. Mishra 《Journal of Electronic Materials》2004,33(5):422-425
In this paper, a novel GaN/AlGaN/GaN high electron mobility transistor (HEMT) is discussed. The device uses a thick GaN-cap
layer (∼250 nm) to reduce the effect of surface potential fluctuations on device performance. Devices without Si3N4 passivation showed no dispersion with 200-ns-pulse-width gate-lag measurements. Saturated output-power density of 3.4 W/mm
and peak power-added efficiency (PAE) of 32% at 10 GHz (VDS=+15 V) were achieved from unpassivated devices on sapphire substrates. Large gate-leakage current and low breakdown voltage
prevented higher drain-bias operation and are currently under investigation. 相似文献
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We have utilized a variable energy positron beam and infrared transmission spectroscopy to study defects in GaAs epilayers
grown at low temperatures (LT-GaAs) by molecular beam epitaxy. We have measured the Doppler broadening of the positron-electron
annihilation gamma ray spectra as a function of positron implantation energy. From these measurements, we have obtained results
for the depth profiles of Ga monovacancies in unannealed LT-GaAs and Ga monovacancies and arsenic cluster related defects
in annealed LT-GaAs. We have also studied the effects of the Si impurities in annealed LT-GaAs. The infrared transmission
measurements on unannealed LT-GaAs furnish a broad defect band, related to As antisites, centered at 0.370 eV below the conduction
band. 相似文献
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电力稳定器在电网中起到稳定电压的作用,一旦该设备出现异常,电网运输电力质量会受到直接影响。面对这种情况,研究一种基于红外成像技术的中低压电网电力稳定器高温运行可靠性图像识别技术。该研究中利用红外成像技术采集电力稳定器图像并实施预处理。分割电力稳定器红外图像,划分目标区域和背景区域。提取目标区域5个直方图-阶统计特征。以5个直方图-阶统计特征为基础,结合判别系数,构建分类器,实现电力稳定器状态识别。针对存在异常的电力稳定器,计算图像目标区域处的相对温差,确定可靠性等级。结果表明:5个测试稳定器中只有2个稳定器处在异常状态,具体为稳定器2中组成部分3异常,稳定器5中组成部分1异常。稳定器2组成部分3相对温差为82.32%,对应可靠等级为2级,可靠性低;稳定器5组成部分1相对温差为91.35%,对应可靠等级为3级,可靠性非常低。对比实验结果表明,所提方法识别准确率达到92.3%以上,优于对比方法,具有更大的应用价值。 相似文献
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《Organic Electronics》2014,15(1):211-215
The understanding of the charge carrier transport in electronic materials is of crucial interest for the design of efficient devices including especially the restraints that arise from device miniaturization. In this work the performance of organic thin-film and single crystal field-effect transistors with the same active material was studied in detail focusing on the high current density regime, where a pronounced non-hysteretic maximum in the transconductance was found. Interestingly, in this operation mode for both, thin films and single crystals, comparable densities of free and gate-induced charge carriers were estimated. Kelvin probe microscopy was used to measure the contact potential difference and the electrical field along the transistor channel during device operation exhibiting the formation of local space charges in the high current density regime. 相似文献
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设计实现了一种高效率的电荷泵电路。利用电容和晶体管对电荷传输开关进行偏置来消除开关管阈值电压的影响。同时,通过对开关管的的衬底进行动态的偏置使得在电荷传输期间当开关管打开时其阈值电压较低,在开关管关断时其阈值电压较高。该电荷泵电路的效率得到了提高。基于0.18μm,3.3V标准CMOS工艺实现了该电路。在每级电容为0.5pF,时钟频率为780KHz,电源电压为2V的情况下,测得的8级电荷泵的输出电压为9.8V。电荷泵电路和时钟驱动电路从电源处总共消耗了2.9μA的电流。该电荷泵电路适合于低功耗的应用。 相似文献
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A high efficiency charge pump circuit is designed and realized. The charge transfer switch is biased by the additional capacitor and transistor to eliminate the influence of the threshold voltage. Moreover, the bulk of the switch transistor is dynamically biased so that the threshold voltage gets lower when it is turned on during charge transfer and gets higher when it is turned off. As a result, the efficiency of the charge pump circuit can be improved. A test chip has been implemented in a 0.18 μm 3.3 V standard CMOS process. The measured output voltage of the eight-pumping-stage charge pump is 9.8 V with each pumping capacitor of 0.5 pF at an output current of 0.18 μA, when the clock frequency is 780 kHz and the supply voltage is 2 V. The charge pump and the clock driver consume a total current of 2.9 μA from the power supply. This circuit is suitable for low power applications. 相似文献
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Mojtaba Maleknejad Somayyeh Mohammadi Hamid Reza Naji Mehdi Hosseinzadeh 《International Journal of Electronics》2018,105(10):1753-1768
In this article, a low-power and energy-efficient hybrid full adder circuit is proposed, which is implemented based on multi-threshold NAND and NOR gates and transmission gate multiplexers. In order to implement this circuit, carbon nano tube field effect transistors are utilised. For evaluating the proposed design, comprehensive simulations are performed with regard to the most important aspects power, delay and power-delay product. The results are presented and displayed the superiority of the proposed cell in different voltage levels, load conditions, temperatures and robustness against process variations. 相似文献
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A novel voltage-controlled oscillator(VCO) topology with low voltage and low power is presented. It employed the inductive-biasing to build a feedback path between the tank and the MOS gate to enhance the voltage gain from output nodes of the tank to the gate node of the cross-coupled transistor. Theoretical analysis using timevarying phase noise theory derives closed-form symbolic formulas for the 1/f~2 phase noise region, showing that this feedback path could improve the phase noise performance. The proposed VCO is fabricated in TSMC 0.13 m CMOS technology. Working under a 0.3 V supply voltage with 1.2 m W power consumption, the measured phase noise of the VCO is –119.4 d Bc/Hz at 1 MHz offset frequency from the carrier of 4.92 GHz, resulting in an Fo M of 192.5 d Bc/Hz. 相似文献
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The application of Futurrex IC1-200 spin-on glass as an insulator for InP metal-insu-lator-semiconductor (MIS) structures
including InP MIS capacitors and InP MIS field-effect transistors (MISFET’s) was investigated. Preliminary measurements of
the elec-trical properties of the spin-on glass were performed using Si MIS structures with the spin-on glass insulator layer.
It was found that the spin-on glass which is subjected to a final curing treatment utilizing a rapid-thermal annealing at
600° C for 5 sec in a O2 ambient exhibits the best electrical properties. However, it was demonstrated by sec-ondary ion mass spectroscopy that when
done on InP, the 600° C rapid-thermal an-nealing resulted in the outdiffusion of indium and phosphorus into the spin-on glass.
The change in the spin-on glass electrical characteristics due to this outdiffusion re-sulted in an instability in the InP
MISFET operation. 相似文献
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We propose a nanoscale single gate ultra thin body intrinsic channel tunnel field effect transistor using the charge plasma concept for ultra low power applications. The characteristics of TFETs (having low leakage) are improved by junctionless TFETs through blending advantages of Junctionless FETs (with high on current). We further improved the characteristics, simultaneously simplifying the structure at a very low power rating using an InAs channel. We found that the proposed device structure has reduced short channel effects and parasitics and provides high speed operation even at a very low supply voltage with low leakage. Simulations resulted in IOFF of ~ 9 × 10-16A/μm, ION of ~20 μA/μm, ION/IOFF of ~2 × 1010, threshold voltage of 0.057 V, subthreshold slope of 7 mV/dec and DIBL of 86 mV/V for PolyGate/HfO2/InAs TFET at a temperature of 300 K, gate length of 20 nm, oxide thickness of 2 nm, film thickness of 10 nm, low-k spacer thickness of 10 nm and VDD of 0.2 V. 相似文献
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A low power high speed MTJ based non-volatile SRAM cell for energy harvesting based IoT applications
Powering billions of devices is one of the most challenging barrier in achieving the future vision of IoT. Most of the sensor nodes for IoT based systems depend on battery as their power source and therefore fail to meet the design goals of lifetime power supply, cost, reliable sensing and transmission. Energy harvesting has the potential to supplant batteries and thus prevents frequent battery replacement. However, energy autonomous systems suffer from sudden power variations due to change in external natural sources and results in loss of data. The memory system is a main component which can improve or decrease performance dramatically. The latest versions of many computing system use chip multiprocessor (CMP) with on-chip cache memory organized as array of SRAM cell. In this paper, we outline the challenges involved with the efficient power supply causing power outage in energy autonomous/self-powered systems. Also, various techniques both at circuit level and system level are discussed which ensures reliable operation of IoT device during power failure. We review the emerging non-volatile memories and explore the possibility of integrating STT-MTJ as prospective candidate for low power solution to energy harvesting based IoT applications. An ultra-low power hybrid NV-SRAM cell is designed by integrating MTJ in the conventional 6T SRAM cell. The proposed LP8T2MTJ NV-SRAM cell is then analyzed using multiple key performance parameters including read/write energies, backup/restore energies, access times and noise margins. The proposed LP8T2MTJ cell is compared to conventional 6T SRAM counterpart indicating similar read and write performance. Also, comparison with the existing MTJ based NV-SRAM cells show 51–78% reduction in backup energy and 42–70% reduction in restore energy. 相似文献
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Nagi Reddy B O. Chandra Sekhar M. Ramamoorty 《International Journal of Electronics》2019,106(8):1164-1183
A single-stage single-switch AC–DC integrated converter is proposed in this paper, as a tight DC voltage regulator with unity input power factor for the fundamental component of the input current. Proposed converter is formed by the integration of buck-boost configuration with a buck converter operated by a single switch. The buck-boost section of the proposed configuration is operated in current discontinuous conduction mode (DCM) to get unity input power factor at the supply terminals and the buck section is operated up to boundary current conduction mode (BCM). The features acquired by the converter operating in complete discontinuous conduction mode (DCM) are unity input power factor, zero-current turn-ON for the Switch, fast and good DC output voltage regulation with extensive conversion range and low voltage stress on the switch. Additionally, the intermediate capacitor voltage stress is independent of converter load variations and so the switch also is subjected to constant peak voltage stress. A comprehensive study is carried out to obtain the necessary design equations. A design model is implemented using simulation and hardware. The results confirm the performance of the proposed configuration. 相似文献
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《AEUE-International Journal of Electronics and Communications》2014,68(8):763-766
There is a considerable interest in the antennas which have high power handling capacity with beam steering functionality. The design of narrow side waveguide slot-array antenna for high power applications is introduced in this paper. An approach to achieve a uniform radiation slot waveguide antenna is presented. The large scale array antenna can be composed of such antenna cells. Moreover, it is possible to realize beam steering in the azimuth direction by adjusting the broad wall dimension of the waveguide. Besides, this slot waveguide antenna is expected to have high power handling capacity in vacuum environment, because there is no dielectric or electric field enhancement inside the antenna. 相似文献
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