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81.
在调制信号下工作的光伏锑化铟红外探测器的探测率和响应率受探测器的交流特性的影响,减小探测器的电容有利于提高其电压响应率和探测率。 相似文献
82.
宽带射频功放晶体管非线性输出电容研究 总被引:2,自引:0,他引:2
分析了GaN(氮化镓)HEMT(高电子迁移率晶体管)非线性输出电容Cout与宽带功放效率的关系。通过建立非线性电路模型分析得出,利用Cout控制漏极端电压电流波形能减轻对谐波阻抗的精确要求,使高效率阻抗区域扩大化,从而使宽带功放匹配变为可能。选用GaN HEMT器件设计2~3 GHz频段射频功率放大器,实测结果为该放大器最高漏极效率(DE)为81.7%,功率附加效率(PAE)78.3%,功率为40.75 dBm。在1 GHz带宽内PAE也可达65%以上。实测结果验证了原理分析的可靠性,提出的方法不仅可用于宽带GaN功率放大器设计,对其他类型的微波功放设计同样有借鉴作用。 相似文献
83.
a- Si∶ H TFT的栅源几何交迭会引起几何寄生电容 ,实验研究表明它并不能完全表征 TFT的寄生效应 ,研究发现由栅极和源极形成的电场的电力线交迭也会导致物理寄生效应且这种效应始终存在 .从 L CD的结构、材料、制备工艺等普遍性出发 ,依据交迭电力线建立了物理寄生效应模型并对其进行了详细的分析和计算 ,实验结果表明该方法是有效可行的 ,从而使 L CD寄生效应有了一个较完美的理论表征和分析计算方法. 相似文献
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Irritation potential of sodium laureth sulfate (SLES) alone, and in combination with lauryl glucoside (LG), polysorbate 20 (PS) and cocoamidopropyl betaine (CAPB) was tested in 13 human subjects. Four main and six sub-formulations were prepared and evaluated. Formulations were applied to the forearm as a 24 h close patch study. Irritation was scored by two different methods using an in vivo clinical protocol based on visual scoring and on the stratum corneum capacitance measurement. Irritation was found to be dose dependent. At 2 mg/patch level ten subjects did not show any skin reaction. At 20 mg/patch level eleven subjects showed a broad range of skin irritation. The highest irritation was observed with the formula that contained SLES, LG, and cocamide DEA together. Among the sub-formulations, cocamide DEA showed the highest irritation grade. A statistically significant correlation was observed between visual, clinical and corneometer scores. It was concluded that the irritation potential of surfactants was related to the total surfactant concentration, application mode, and the thermodynamic activity of molecules in the solution as well as the chemical structure of the surfactant molecules. 相似文献
86.
The fabrication of hierarchically structured Ni(OH)2 monolayer hollow‐sphere arrays with the shell composed of building blocks of nanoflakelets is reported on p. 644 by Weiping Cai and co‐workers. The morphology can be easily controlled by the synthesis parameters, and the arrays show a tunable optical transmission stop band. Tuning can be achieved by changing the size or morphology of the hollow spheres. Such arrays may have potential applications in optical devices, photonic crystals, and as sensors for gas detection. The fabrication of a hierarchically structured Ni(OH)2 monolayer hollow‐sphere array with the shell composed of building blocks of nanoflakelets is demonstrated based on a colloidal monolayer and electrochemical deposition. The morphology can be easily controlled by the colloidal monolayer and deposition parameters. Importantly, such monolayer hollow‐sphere array shows a morphology‐ and size‐dependent tunable optical transmission stop band. This stop band can be easily tuned from 455–1855 nm by changing the size of the hollow spheres between 1000 and 4500 nm, and also fine‐adjusted by changing the deposition time. The array exhibits a nearly incident‐angle‐independent position of the stop band that 3D photonic crystals do not possess. This structure may have potential applications in optical devices, photonic crystals, and sensors for gas detection. 相似文献
87.
An analytical two-dimensional capacitance-voltage model for AlGaN/GaN high electron mobility transistor (HEMTs) is developed, which is valid from a linear to saturation region. The gate source and gate drain capacitances are calculated for 120 nm gate length including the effects of fringing field capacitances. We obtain a cut-off frequency (fT) of 120 GHz and maximum frequency of oscillations (fmax) of 160 GHz. The model is very useful for microwave circuit design and analysis. Additionally, these devices allow a high operating voltage VDS, which is demonstrated in the present analysis. These results show an excellent agreement when compared with the experimental data. 相似文献
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