MOSFET亚阈特性分析与低温按比例缩小理论的研究

器件尺寸按比例缩小是实现超大规模集成电路的有效途径，但寄生和二级效应却将器件限在一定的水平，本文在对比分析常温与低温下小尺寸器件效应的基础上，重点研究了ＭＯＳ器件亚阈特性对器件性能及按比例缩小的影响，并根据低温工作的特点，提出了ＭＯＳ器件一种低温按比例缩小规则，该原则对低温器的优化设计，从而更大程度在提高电路与系统性能具有重要的指导意义。     

High sensitivity CW-cavity ring down spectroscopy of water in the region of the 1.5 μm atmospheric window

The absorption spectrum of natural water vapour around 1.5 μm has been recorded with a typical sensitivity of 5 × 10⁻¹⁰ cm⁻¹ by using a CW-cavity ring down spectroscopy set up based on fibred DFB lasers. A series of 31 DFB lasers has allowed a full coverage of the 6130.8-6748.5 cm⁻¹ (1.63-1.48 μm) region corresponding to the H transparency band of the atmosphere. The line parameters (wavenumber and intensity) of a total of 5190 lines, including 4247 lines of water vapor, were derived by a one by one fit of the lines to a Voigt profile. Different isotopologues of water (H₂¹⁶O, H₂¹⁸O, H₂¹⁷O, and HD¹⁶O) present in natural abundance in the sample contribute to the spectrum. For the main isotopologue, H₂¹⁶O, 2130 lines were measured with line intensities as weak as 10⁻²⁹ cm/molecule while only 926 lines (including a proportion of 30% inaccurate calculated lines) with a minimum intensity of 3 × 10⁻²⁷ cm/molecule are provided by the HITRAN and GEISA databases. Our comparison in the whole 5750-7965 cm⁻¹ region, has also evidenced that an error in the process of conversion of the intensity units from cm⁻²/atm to cm⁻¹/(molecule × cm⁻²) at 296 K, has led to H₂¹⁶O line intensities values listed in the HITRAN-2000 database, systematically 8 % below the original FTS values. The rovibrational assignment was performed on the basis of the ab initio calculations by Schwenke and Partridge with a subsequent refinement and validation using the Ritz combination principle together with all previously measured water transitions relevant to this study. This procedure allowed determining 172, 139, 71, and 115 new energy levels for the H₂¹⁶O, H₂¹⁸O, H₂¹⁷O, and HD¹⁶O isotopologues, respectively. The results are compared with the available databases and discussed in regard of previous investigations by Fourier transform spectroscopy. The spectrum analysis has showed that most of the transitions which cannot be assigned to water are very weak and are due to impurities such as carbon dioxide and ammonia, leaving only about 3% of the observed transitions unassigned. The interest of a detailed knowledge of water absorption for trace detectors developed in the 1.5 μm range is underlined: for instance HDO contributes significantly to the considered spectrum while no HDO line parameters are provided by the HITRAN database.     

狭义相对论效应──运动时钟变慢的计算机模拟演示实验

利用精炼的C语言进行程序设计，定量模拟狭义相结论的运动时钟变慢，并对处于两种不同时空观的时钟运行进行对比，使得时间膨胀效应变得直观。     

The role of various binding materials for trace elemental analysis of powder samples using laser-induced breakdown spectroscopy

Study of various binding materials like potassium bromide, poly(vinyl alcohol), starch, silver and aluminum has been carried out using laser-induced breakdown spectroscopy (LIBS). The role of matrix effects using these five binders on LIBS signal intensity was investigated for better performance of LIBS technique as a quantitative analytical tool. For comparative study of different binders, the signal intensity of different Mg lines at 518.3, 517.2, 383.8 and 279.5 nm wavelengths were recorded for pellets prepared with known concentrations of Mg in these binders. The influence of laser energy on ablated mass under different binding materials and its correlation with LIBS signal intensity has been explored. Optical scanning microscopy images of the ablated crater were studied to understand the laser ablation process. The study revealed that the binding material plays an important role in the generation of LIBS signal. The relative signal intensity measured for a standard Mg line (at 518.3 nm) were 735, 538, 387, 227 and 130 for potassium bromide, starch, poly(vinyl alcohol), silver and aluminum as binders, respectively. This indicates clearly that potassium bromide is better as a binder for LIBS studies of powder samples.     

Bioactive steroidal glycosides from the marine sponge Erylus lendenfeldi

Bioassay-guided fractionation of the methanol extract of Erylus lendenfeldi using engineered strains of budding yeast (Saccharomyces cerevisiae) has resulted in the isolation of the known compound eryloside A (1) and two new compounds, erylosides K (2) and L (3). The structures were established based mainly on 1D and 2D NMR data. The absolute stereochemistry of eryloside A, which had never been fully characterized, was determined using the modified Mosher's method. The absolute stereochemistry of eryloside K was determined by comparison with tetrahydroeryloside A. Compounds 1-3 exhibited selective cytotoxicity against a yeast strain (Δrad50) deficient in double strand break (DSB) repair.     

低电压驱动的硅基Ka波段级联式MEMS移相器

通过在共平面波导上周期性地分布微机械电容,外加电压驱动改变电容值,可实现级联式MEMS移相器.本文讨论了优化相移特性对共平面波导特性阻抗及下拉电压的要求,通过工艺参数优化制备了高阻硅基上的Ka波段级联式MEMS移相器,测试结果表明制备器件具有较低的驱动电压,8V时即产生明显的相移量,在36GHz处15V驱动电压时相移量为118°,25V时为286°.对微结构弹性膜的机械振动寿命测试表明,13级级联的MEMS移相器所有弹性膜同步振动的寿命为3×10⁶次.为器件的实用化提供了重要保障.     

Three‐dimensional wave impact on a rigid structure using smoothed particle hydrodynamics

Navier–Stokes computations of a wave–structure interaction are performed with the aim of assessing the potential of smoothed particle hydrodynamics to accurately estimate impact loading time history. A three‐dimensional dam‐break flow with a rectangular column located downstream is considered. The net force and impulse exerted on the column is monitored throughout the simulation with the results correlating well with existing experimental data. Initial and boundary conditions and numerical parameters are varied and their effect on the column load investigated. The column load is found to be most sensitive to the choice of boundary treatment. Copyright © 2011 John Wiley & Sons, Ltd.     

一种带改进开关和使用新型按比例缩小策略的10位120兆的流水线模数转换器

这篇文章介绍了一种精度为10比特,采样率为120兆的双通道流水线模数转换器(ADC)。这个模数转换器利用了体效应来改善开关的导通性能。在版图绘制中应用了一种新型的按比例缩小的策略。基于0.18μm的CMOS工艺,ADC的整个版图面积为2.05x1.83 mm2。在采样频率为120兆,输入信号频率为4.9兆的情况下,无杂散动态范围达到了74.32dB,信号噪音失真比为55.34dB,3伏供电电压下每通道的功耗为220毫瓦。     

一种基于频分复用信号的宽带数字收发设计

介绍了一种基于频分复用信号的宽带数字收发设计。根据软件无线电基本理论给出了系统的硬件具体实现和软件处理流程,描述了基于FPGA平台的并行FIR滤波器和并行CIC滤波器的高效实现方法。给出了宽带数字收发系统的仿真和测试结果。该系统硬件结构简洁,逻辑资源开销小,通用性和扩展性强。     

工艺参数对低压TVS器件耐压的影响

目前低压瞬间电压抑制(TVS)二极管工艺参数的研究还不够深入.从深p型(DP)基区杂质浓度、杂质注入能量及基区尺寸控制三个方面探究了工艺条件对低击穿电压的影响.当DP注入剂量小于6.0×1014cm-2时,pn结以雪崩击穿为主,耐压大于6V.DP注入能量在50 keY以下与高浓度n+区复合形成的pn结雪崩击穿耐压大于6V;当控制基区尺寸使n+集电区与DP基区的间距大于1.2 μm时击穿电压保持为7V,但是随着n+与DP基区的间距增加,电流导通路径受到挤压变窄,在相同的反向测试电流下,器件耐压略有提升.通过对单向TVS工艺仿真优化,选择了关键工艺参数,并进行了工程实验,制备了兼具低电容和高抗ESD能力的TVS器件,保证了对主器件实施可靠的保护.