一种适用于内嵌时钟串行链路的5Gbps小面积CDR

本文提出了一种支持多标准的具有系数可调的均衡器和宽跟踪能力的时钟数据恢复电路。基于对系统参数和一阶 bang-bang 时钟数据恢复电路的环路特性分析,推导出电路设计参数。考虑到抖动性能,追踪能力以及芯片面积,文中采用了一阶数字滤波器和6-bit DAC以及高线性度的相位插值器实现了高相位调整精度和小面积的时钟恢复电路,同时该结构实现了±2200ppm的频偏跟踪能力,使得该结构适用于不同源的高速串行传输系统,尤其是内嵌时钟结构。该设计已经在55nm CMOS工艺上流片验证,测试结果显示符合误码率的要求以及抖动容忍规范。该测试芯片整体面积是0.19mm2,其中时钟恢复电路只占0.0486mm2 而且该电路工作在5Gbps,供电电压为1.2V时,只消耗30mW。     

Tavis-Cummings模型中三体纠缠态纠缠量的演化特性

研究两个全同二能级原子与单模场相互作用的Tavis-Cummings模型中的量子纠缠.在场和两原子初始分别为真空场和纠缠或非纠缠状态下，得出体系状态将演化为三体近似W纠缠态.通过对纠缠量的计算得出：该三体近似W纠缠态纠缠量的演化特性将随三体所处的初始状态、原子间及原子与场间的耦合系数、失谐程度、原子反转粒子数的变化而变化.值得一提的是可得出原子间耦合作用强度对纠缠量的非线性效应，并且纠缠量展现出与原子反转粒子数一致的周期振荡现象. 关键词： W纠缠态 纠缠量 反转粒子数     

镜面起伏对1.55μm Si基MEMS光滤波器的影响

用传输矩阵方法,在简化的光学模型基础上,分别讨论了分布式Bragg反射镜DBR(Distributed Bragg Reflector)的生长精度及镜面起伏对1.55 μm Si基MEMS(Micro-Electro-Mechanical-System)可调谐光滤波器透射谱的影响.计算表明:DBR生长误差仅使主透射峰位置发生变化,而镜面起伏是导致主透射峰性能劣化的主要原因,它使得FWHM增大,透射峰强度下降.理论计算结果能较好地解释实验现像.在此基础上,进一步讨论了引起镜面起伏的多种原因,并提出了可能的解决方法.     

半金属锑薄膜中电子动力学研究

采用时间分辨抽运-探测透射光谱,研究了不同波长和不同激发流密度下半金属Sb薄膜的超快电子动力学过程.透射变化率的时间延迟扫描曲线显示在延迟零点附近出现强的振荡,正的吸收饱和峰在亚皮秒时间内衰减为负的吸收增强峰.之后,负的吸收增强峰在数皮秒时间内甚至再次演变为吸收饱和.正饱和峰和负吸收峰幅度正比于激发流密度和光波长.对这些现象进行了分析,引入“缺陷”态模型及考虑“缺陷”态对光激发电子的快速俘获和逐渐释放,能够合理、半定量地解释实验观察到的所有现象. 关键词： 半金属 杂质或缺陷态 电子动力学 抽运-探测光谱     

单行载流子光电探测器中空间电荷屏蔽效应理论分析和实验研究

本文优化设计和外延生长了一种单行载流子(UTC)光电探测器有源区结构,并且采用微电子工艺制备了台面尺寸为30μm的UTC光电探测器.同时,采用了漂移-扩散模型对该有源区结构进行了理论模拟,从载流子浓度和空间电场角度重点分析研究了空间电荷屏蔽效应对UTC光电探测器直流饱和特性影响的物理机理.UTC光电探测器理论模拟结果与实测数据基本相符.     

Microwave-absorbing properties of shape-optimized carbonyl iron particles with maximum microwave permeability

The microwave-absorbing properties for different shapes of carbonyl-iron particles prepared by the high-energy planetary ball milling with 40 vol% in epoxy resin matrix have been investigated. Higher value of magnetic permeability and permittivity can be obtained in the composites for thin flake carbonyl iron than spherical powders. The results are attributed to reduction of eddy current loss, orientation of magnetic moment and space-charge polarization with the shape change from spherical powders to thin flake particles. As the iron flakes with 0.4 μm in thickness as the absorbent fillers, the minimum RL value of −6.20 dB was observed at 4.57 GHz with thickness of 1 mm. The minimum reflection loss (RL) shifts to lower frequency and the value declines with change from spherical powders to thin flakes. It results from the considerable dielectric loss in the absorbing materials.     

Preparation of SiC nanowires with fins by chemical vapor deposition

SiC nanowires with fins have been prepared by chemical vapor deposition in a vertical vacuum furnace by using a powder mixture of milled Si and SiO₂ and gaseous CH₄ as the raw materials. The products were characterized by field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). These investigations confirm that the nanowires with fins are cubic β-SiC. The diameter of the fins is about 100–120 nm and the diameter of the inner core stems is about 60–70 nm. The formation process of the β-SiC nanowires with fins is analyzed and discussed briefly.     

Wavefront aberrations in the accommodated human eye based on individual eye model

In this research, we firstly construct individual eye models based on the wavefront and the measured cornea structure of the eyes. Then we analyze the influence of accommodation on the wavefront aberrations based on individual eye model. The individual eye model has the same wavefront aberration as that measured from Hartmann–Shack wavefront sensor. The optical design software ZEMAX is used to construct the individual eye models for 20 normal eyes. Accommodative conditions are from 0 to –4 diopter in steps of one diopter. The variations of the total, the spherical, the coma and the higher-order root-mean-square wavefront aberrations, as accommodations, are illustrated. Influence of accommodation on wavefront aberration varies from individual to individual, and the variation magnitude is independent of the magnitude of the wavefront aberration of the eye.     

纳米α-Al2O3磨料抛光单晶硅片光滑表面的形成机理

"将纳米α-Al2O3粉体配制成抛光液并冷冻成冰结抛光垫对单晶硅片进行了抛光,用原子力显微镜观察了抛光表面的微观形貌并测量了其表面粗糙度,采用透射电镜观察了单晶硅片抛光后的断面形貌．为进一步分析抛光过程中的化学作用机理,采用X射线光电子能谱分析了单晶硅片抛光后表面的化学成分．利用纳米压痕仪的划痕附件对单晶硅片进行了划痕测试,研究了抛光过程中的机械作用机理．结果表明纳米α-Al2O3磨料冰冻抛光单晶硅片时,在1 mm￡1 mm的范围内得到了微观表面粗糙度为0.367 nm的超光滑表面,亚表面没有任何损伤,材     

Intense 974 nm emission from ErxYb2−xSi2O7 films through efficient energy transfer up-conversion from Er3+ to Yb3+ for Si solar cell

The optical properties of the Er_xYb_2?xSi₂O₇ thin films were investigated by photoluminescence measurements and the intense 974 nm light emission was observed. The 974 nm emission was mainly from the transition ²F_5/2 to ²F_7/2 level of Yb³⁺ upon exploring energy-transfer via up-conversion at Er^{3+ 4}I_13/2 level. Under 972 nm excitation, the lifetime at Er^{3+ 4}I_13/2 level reaches up to 4 ms for film containing 2 at% Er³⁺, while decreases to about 20 μs as the film is pumped by 488 nm. This confirmed that the energy transfer up-conversion process was the dominant transition at Er^{3+ 4}I_13/2 level. This may be of interest to improve the solar cells′ efficiency by placing this film at the rear of cell, converting the near-infrared photons between 1480 nm and 1580 nm to just above the Si bandgap.