群时延精确设计的全差分四阶Bessel滤波器

采用MOS管有源电阻,提出了一种全差分R-MOSFET-C四阶Bessel有源低通滤波器,.通过调节工作于亚阈值区的CMOS管的沟道导纳补偿电阻值的大小,能抵消集成电路制造工艺中电阻值的一致偏差,实现Bessel有源滤波器群时延的精确设计.根据无源滤波器的状态方程完成有源滤波器的综合,应用3.3V,0.5μm CMOS工艺完成了群时延大小为0.75μs的四阶Bessel低通滤波器的管极计算机仿真,仿真结果表明所提电路正确有效,适于全集成.     

一种检验定性指标的有效方法

介绍了一种检验定性指标的有效方法,可用于确定产品的合格率和评价检验人员的检验水平。用该方法分析了某厂产品的一项实际指标,合格率为91 4%,还对该厂10名检验员的检验水平作了客观的评价。     

铜互连中SiCOF/a-C∶F双层低介电常数薄膜的制备和表征(英文)

用等离子体化学气相淀积系统制备了一种新颖的SiCOF/a-C∶F双层低介电常数介质薄膜,并用红外光谱表征了该薄膜的化学结构.通过测量介质的折射率发现该薄膜长时间暴露在空气中,其光频介电常数几乎不变.然而,随退火温度的增加,其光频介电常数则会减小.基于实验结果讨论了几种可能的机理.二次离子质谱分析表明在Al/a-C∶F/Si结构中F和C很容易扩散到Al中,但在Al/SiCOF/a-C∶F/Si结构中,则没有发现C的扩散,说明SiCOF充当了C扩散的阻挡层.分析还发现在SiCOF和a-C∶F之间没有明显的界面层.     

一种低压低功耗SRAM/SOI单元设计

提出一种改进4管自体偏压结构SRAM/SOI单元.基于TSUPREM4和MEDICI软件的模拟和结构性能的分析,设计单元结构并选取结构参数.该结构采用nMOS栅下的含p+埋沟的衬底体电阻代替传统6管CMOSSRAM单元中的pMOS元件,具有面积小、工艺简单的优点.该结构可以在0.5V的电源电压下正常工作,与6管单元相比,该单元瞬态响应正常,功耗只有6管单元的1/10,满足低压低功耗的要求.     

ACCELERATION AMBIGUITY FUNCTION OF RADAR SIGNALS AND ITS APPLICATION

High acceleration of radar targets is analyzed using Acceleration Ambiguity Function(AAF). The acceleration resolution based on AAF is defined. The AAF and acceleration resolution of rectangle pulse signal are derivated and the conclusion that its acceleration resolution is in inverse proportion with the square of its duration is drawn. In the end, these conclusions are applied to the parameter designing and performance evaluation for a certain type of pulse Doppler radar.     

基于宽带毫米波工作体制的雷达目标识别方法探讨

对基于宽带毫米波工作体制的雷达目标特征获取和识别方法进行了综合分析和探讨.表明:在毫米波照射下,雷达目标可模型化为由多个散射中心组成的扩展目标;只要发射信号有足够的带宽,就可以从回波信号中获得各散射中心的空间分布、类型等特征;仿真结果说明,这种方法对高频区复杂目标的识别是有效的.     

Effect of distortion in electron impact excitation in Coulomb-projected Born approximation

We have calculated total and differential cross-sections for 1s →ns (n = 2, 3, 4) electron impact excitation of hydrogen and hydrogenic ions at various energies in Coulomb-projected Born approximation. Distortion due to static interactions, target polarization and exchange effects has been incorporated in the initial channel. The present calculations have been compared with other theoretical and experimental results.     

111In–L–LDL and 153Gd–L–LDL as radiotracers for detection of AR4‐2J rat pancreatic tumors

Pancreatic cancer has an extremely poor prognosis, due, in part, to lack of methods for early diagnosis. The present study was designed to evaluate the potential of labeling low‐density lipoprotein (LDL) with a radionuclide using a lipid chelating agent, bis(stearylamide) of diethylenetriaminepentaacetic acid (L), to detect pancreatic tumors by gamma‐scintigraphy. Previous studies indicated that the difficulty of visualization of pancreatic tumors was due to their poor vascularization. This study compares the ability of two radiotracers, ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL to target highly vascularized rat pancreatic tumors (AR4‐2J) implanted in nude mice. Biodistribution studies showed that the tumor uptake of ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL tracers was twofold and fivefold higher respectively than with the controls (¹¹¹In citrate and ¹⁵³Gd citrate respectively). These tracers would thus be suitable for scintigraphic imaging. We show here that LDL could be employed as a delivery system for tracers such as ¹¹¹In or ¹⁵³Gd when these two radionuclides are complexed by a lipid‐chelating anchor, and that ¹¹¹In–L–LDL and ¹⁵³Gd–L–LDL enabled better visualization of the pancreatic tumor tissues, with a better result with ¹⁵³Gd–L–LDL. Copyright © 2004 John Wiley & Sons, Ltd.     

低k氟化非晶碳层间介质对芯片性能的影响

讨论了通过合理设计的工艺流程将低k氟化非晶碳材料应用到制造工艺中作为互连介质对集成电路性能的影响。基于一个互连结构简化模型计算出采用低k氟化非晶碳材料作为互连介质后RC延迟、功率耗散和线间串扰的变化情况。采用低k氟化非晶碳介质后,RC延迟和功率耗散随着互连长度的增大而减小,线间串扰也得到显著抑制。     

低速二维流动的粒子仿真研究

本文运用信息保存法对低速二维的流动现象进行模拟，考察了低速条件下的有限平板绕流以及微槽道气体流动问题。研究表明：在对低速流动的模拟过程中，运用IP法在能够获得较好的结果的同时，具有比DSMC方法更高的计算效率。