外环式减薄进给系统研究

通过对减薄设备发展过程的研究,提出了一种由外环式磨削进给方式组成的外环式减薄系统。该系统可实现在减薄过程中对芯片磨削与研磨的最佳组合。     

渗浸陶瓷活塞环

利用低温(<300℃)等离子化学气相沉积技术,在活塞环表面生成一层双向扩散的微晶体与网状结构并存的氮化硼—氮化硅金属复合陶瓷层,提高环的表面硬度、耐磨性,降低摩擦系数。在镀铬环表面生成复合陶瓷层后,常温下导热系数可提高42%,并随温度升高呈指数规律上升,从而减少环的工作温度,减少形变,提高气密性,改善发动机整体性能。使用渗浸陶瓷活塞环,发动机可高效节油,提高使用寿命,改善尾气排放。     

一种改进的差分环型振荡器相位噪声模型

在Razavi模型和Weigandt模型的基础上,提出了一种改进的差分环型振荡器相位噪声模型.新模型考虑了环振非线性对相位噪声的影响,从新的角度讨论了相位噪声的三种发生机制和影响,讨论了闪烁噪声的优化方法,得到了新的相位噪声模型,并依此着重分析了对管尺寸和环振级数对相位噪声的影响.最后,分析了低噪声设计的一些原则.采用CSM0.35μm工艺进行了流片验证,模型与测试结果能够很好地吻合     

热风炉输送管路内涡流激振作用的流动特征

以具有3个90°弯头和1个文氏管为特征的鞍钢新1号高炉热风炉助燃空气输送管路为物理模型,进行了流场仿真计算,预测到圆管内二次流旋涡、边界层分离的壁涡以及纵向旋转变化等同时存在的复杂流动特征,与过去的研究结果相一致,证实了管路中旋涡和非线性汇集、膨胀流与管壁之间的相互作用,是造成热风炉管路系统出现共振的激振力之一。从而提醒人们要注重合理的管路设计与工艺参数的结合,同时为热风炉系统的振动诊断分析提供了一种依据和方法。     

Security of polarization-shift keying chaos optical communication system

To evaluate the security of a chaos optical communication system employing the polarization-shift keying (PolSK) modulation technology, its chaos characteristic needs to be verified. In this paper, an analysis was done for the signal of this system. Three methods were used to judge whether the signal was maintaining chaos characteristics or not: watching the strange attractor in three-dimensional phase space, computing the largest Lyapunov exponent by the equation which meets and Wolf's method, and evaluating the self-power spectrum density function. As a result, the strange attractor was clearly watched, the largest Lyapunov exponent was positive 0.0364 and 0.0106 respectively,and the self-power spectrum was wide and continuous with the noise background. The evaluation of chaos for the signal transmitted in the system is therefore presented. On the other hand, the minimal embodied dimension of the signal was given by the false nearest neighbors (FNN) method and it reached 6, which showed the higher dimension chaos characteristics of the system.Adding the analysis of the ability of anti-attack for the system, it is concluded that the system has higher security than the normal chaos masking schemes.     

ZnO Thin Film, Device, and Circuit Fabrication using Low-Temperature PECVD Processes

We report undoped ZnO films deposited at low temperature (200°C) using plasma-enhanced chemical vapor deposition (PECVD). ZnO thin-film transistors (TFTs) fabricated using ZnO and Al₂O₃ deposited in situ by PECVD with moderate gate leakage show a field-effect mobility of 10 cm²/V s, threshold voltage of 7.5 V, subthreshold slope <1 V/dec, and current on/off ratios >10⁴. Inverter circuits fabricated using these ZnO TFTs show peak gain magnitude (dV _out/dV _in) ~5. These devices appear to be strongly limited by interface states and reducing the gate leakage results in TFTs with lower mobility. For example, ZnO TFTs fabricated with low-leakage Al₂O₃ have mobility near 0.05 cm²/V s, and five-stage ring-oscillator integrated circuits fabricated using these TFTs have a 1.2 kHz oscillation frequency at 60 V, likely limited by interface states.     

门电路环形振荡器仿真研究

在测量门电路的传输延迟时间时,通常用门电路环形振荡器,但门电路环形振荡器振荡频率较高,对实验仪器设备的要求也较高,用仿真实验的方法有直观明了的优点,所以在数字电路教学中常用仿真的方法来进行实验.然而,在用仿真方法进行实验分析时,实验结果和实物实验或理论分析会存在一些差异.分别用EWB的2种版本仿真软件EWB 5和Multisim 9对门电路环形振荡器进行仿真,分析出现差异的原因,指出在用仿真方法进行数字电路仿真分析和设计时要注意的问题.     

一种低电压低功耗的环形压控振荡器设计

提出了锁相环的核心部件压控振荡器(VCO)的一种设计方案.该压控振荡器采用全差分环形压控振荡器结构,其延迟单元使用交叉耦合晶体管对来进行频率调节.基于SMIC0.18μmCMOS工艺,用Hspice对电路进行了仿真.仿真结果表明,该压控振荡器具有良好的线性度,较宽的线性范围以及高的工作频率,在1.8V的低电源电压下,振荡频率的变化范围为402～873MHz,中心频率在635MHz,功耗仅为6mW,振荡在中心频率635MHz时的均方根抖动为3.91ps.     

单场限环结构的表面电场分布及环间距的优化

基于横向扩散与纵向扩散构成的冶金结边界为椭圆形这一特点,讨论单场限环结构表面电场强度的分布,给出表面电场强度、主结及环结分担电压的解析表达式。在纵向结深和掺杂浓度一定的条件下,根据临界电场击穿理论,讨论环间距的优化设计方法。单场限环结构主结环结间表面电场强度的绝对值曲线近似呈抛物线,最大电场位于主结处。随着环间距的增大,最大电场变大;随着横向扩散深度的增大,最大电场变小。环右侧最大电场也出现在结处,随着环间距和横向扩散深度的增加,最大电场均减小。在场限环结构中,当主结和环结在表面处的最大电场强度均等于临界电场强度时,击穿电压达到最大值,此时所对应的环间距为最佳环间距。