共查询到20条相似文献,搜索用时 69 毫秒
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以固态半导体器件为基础,基于超快电子学中的晶体管雪崩导通理论,利用脉冲耦合原理,在时域上将多路高压皮秒脉冲耦合输出,获得了超宽带高功率脉冲。通过四路脉冲耦合实验验证了该设计思路的可行性,提高了输出脉冲功率。实验中,单路高压皮秒脉冲的幅度为1.33kV,宽度为770ps,峰值抖动≤1%,脉宽抖动≤1%,四路脉冲耦合后,输出脉冲幅度为2.66 kV,宽度为875 ps,峰值抖动≤1%,脉宽抖动≤1%。该方法可以推广至多路脉冲耦合,获得更高的功率。 相似文献
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针对现有热特性测试及评价标准尚不完善的问题,以功率型发光二极管(LED)的精确热特性测试及评价为目标,采用光热一体化测试技术对不同的LED灯珠进行了热特性测试,研究了测试电流对K值标定及结温测试的影响,分析了热特性随环境温度的变化情况,提出了热性能测试及评价的合理建议。研究结果表明:测试电流对K值标定及结温测试有较大影响,测试电流的合理选取与芯片本身及功率的大小有关;材料的热导率随环境温度变化波动,对于某些高温使用环境,仅25℃的热性能参数数据并不能准确反应LED的热特性;热阻测试的准确性与光功率有关,光热一体化测试有利于得到准确的热特性数据。 相似文献
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设计了一种基于ADP3806的高功率发光二极管(LED)的高效驱动电路。ADP3806是一款开关模式电源控制器,拥有双环路恒定电压和恒定电流控制、远程精确电流检测以及关断和可编程可同步开关频率,能提供恒定电流。同时在设计中利用单端原边电感转换器(SEPIC),其可以提供一种可以高于或低于输入电压的输出电压,在适当的占空比下工作,使连续传导模式(CCM)和脉冲宽度调制(PWM)控制变得简单,提高了效率,并且避免由变压器泄漏电感带来的电压尖峰和振铃。从而在需要进行升压和降压转换来同时驱动多个高功率LED的场合,这个设计是非常适合的。 相似文献
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本文着重介绍任意个(1 ̄20个)高功率LED串联的恒流源驱动器。它能有效克服并联LED驱动器的缺点,明显扩展和提高了市场上已出现的高功率LED串联驱动器的应用范围和性能。 相似文献
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Han-Kuei Fu Chin-Wei Lin Tzung-Te Chen Chiu-Ling Chen Pei-Ting Chou Chien-Jen Sun 《Microelectronics Reliability》2012,52(5):866-871
Environmental concerns have led to the popularity of solid stating lighting, in which a high quality white light source depends on the stable property of light emitting diode. This study examines a white-light high-power light-emitting diode composed of a blue chip and yellow phosphor. A white-light light-emitting diode can be divided into four parts—a blue chip, yellow phosphor, transparent silicone, and reflector. In a transient experiment, the wavelength shift of the blue chip markedly affects the conversion efficiency of yellow phosphor, causing white-light deviation, especially in the sharp variation region of absorption of yellow phosphor. A series of short-term experiments was conducted to identify the mechanisms of color deviation between yellow phosphor and transparent silicone. The robustness of commercial phosphor and silicone was much stronger than expected. In addition to a yellowed reflector and blue chip degradation, several combinations of degradation mechanisms between yellow phosphor and transparent silicone. In a long-term experiment, damaged silicon confines blue light resulting in warm white light. Two suggestions are provided to obtain white-light light-emitting diodes with high color reliability. 相似文献
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Efficiencies are calculated for quantum-dot apertured-microcavity light-emitting diodes. Although the maximum efficiency depends strongly on the quantum-dot inhomogeneous broadening, greater than 20% efficiency is calculated for a small-sized apertured microcavity, even for an inhomogeneous linewidth as large as 30 meV. The efficiency can be increased to 40% if the inhomogeneous linewidth is reduced to 10 meV and to more than 60% if the inhomogeneous linewidth is eliminated to leave a homogeneous linewidth of 6.6 meV. The maximum output powers are ~40 nW, although a microarray can increase this value. For the case of a single quantum dot, an efficiency >80% is estimated for a submicron apertured-microcavity, with a maximum output power of ~3 nW 相似文献
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The influence of temperature on the parameters of the band-to-band emission spectrum of a light-emitting diode based on single-crystal silicon was investigated; the unprecedentedly high stability against variations in temperature was observed for both the electroluminescence intensity at the peak of the spectral distribution (I EL m ) and the wavelength corresponding to this peak (λm). The internal quantum efficiency of the light-emitting diode at room temperature is estimated as no lower than 0.1%. The value of I EL m varies by no more than ~10% as the temperature is varied from 120 to 300 K. The value of λm remains virtually constant in the temperature range of 200–300 K. The unprecedentedly high stability of λm is related to interference effects in the oxide film through which the radiation of the light-emitting exits. It is shown that one of the important factors that govern the temperature stability of I EL m is a decrease in the lifetime of the minority charge carriers with decreasing temperature. 相似文献
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《Solid-state electronics》1999,43(9):1747-1753
Static J–V, σ–J, γ–J characteristics based on numerical 1D simulation for Me–n–n+ and Me–n structures are given. The forward voltage drop of the former structure is less then the last one under high level injection because of LH (nn+) junction reflecting properties with respect to minority carriers. Holes stimulate base conductivity modulation but, in spite of this, the hole current gives a negligible contribution to the total current. It is shown that the injection ratio is a less significant parameter compared to base conductivity modulation if it is necessary to estimate charge storage. Influence of substrate is investigated. In addition to forming an LH barrier, the substrate acts as a source of majority carriers and defines the forward voltage drop across the diode structure. Bandgap narrowing in the substrate is taken into account. A comparison with experimental results is also given. 相似文献
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Conventional GaN-based flip-chip light-emitting diodes (CFC-LEDs) use Au bumps to contact the LED chip and Si submount, however the contact area is constrained by the number of Au bumps, limiting the heat dissipation performance. This paper presents a flat surface high power GaN-based flip-chip light emitting diode (SFC-LED), which can greatly improve the heat dissipation performance of the device. In order to understand the thermal performance of the SFC-LED thoroughly, a 3-D finite element model (FEM) is developed, and ANSYS is used to simulate the thermal performance. The temperature distributions of the SFC-LED and the CFC-LED are shown in this article, and the junction temperature simulation values of the SFC-LED and the CFC-LED are 112.80 ℃ and 122.97℃C, respectively. Simulation results prove that the junction temperature of the new structure is 10.17 ℃ lower than that of the conventional structure. Even if the CFC-LED has 24 Au bumps, the thermal resistance of the new structure is still far less than that of the conventional structure. The SFC-LED has a better thermal property. 相似文献
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《Organic Electronics》2008,9(3):279-284
A highly efficient deep blue polymer light-emitting diode based on poly(9,9-dioctylfluorene) is demonstrated. The performance is found to increase significantly with the molecular weight. Two different molecular weights are compared, one is 71,000 and the other is 365,000. The electroluminescent efficiency and color stability are improved by slightly doping hole traps into the emission layer and bilayer structure. The maximum efficiency is 3.8 cd/A with the corresponding external quantum efficiency of 3.7% at deep blue with Commission Internationale de L’Eclairage (CIE) coordinate at (0.15, 0.09). Stable blue emission is maintained up to 6600 cd/m2 without growth of green shoulder in emission spectrum. 相似文献
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Improvement of InGaN-GaN light-emitting diode performance with a nano-roughened p-GaN surface 总被引:2,自引:0,他引:2
Hung-Wen Huang C.C. Kao J.T. Chu H.C. Kuo S.C. Wang C.C. Yu 《Photonics Technology Letters, IEEE》2005,17(5):983-985
This investigation describes the development of InGaN-GaN light-emitting diode (LED) with a nano-roughened top p-GaN surface which uses Ni nano-mask and wet etching. The light output of the InGaN-GaN LED with a nano-roughened top p-GaN surface is 1.4 times that of a conventional LED, and wall-plug efficiency is 45% higher. The operating voltage of InGaN-GaN LED was reduced from 3.65 to 3.5 V at 20 mA and the series resistance was reduced by 20%. The light output is increased by the nano-roughening of the top p-GaN surface. The reduction in the series resistance can be attributed to the increase in the contact area of nano-roughened surface. 相似文献