芯片粘接空洞对功率器件散热特性的影响

芯片粘结层的空洞是造成功率半导体芯片由于散热不良而失效的主要原因.运用有限元法对芯片封装结构进行了热学模拟分析,研究了粘结层材料、粘结层厚度、粘结层空洞的面积、空洞的位置对芯片温度分布以及芯片最高温度造成的影响.对标准中规定应避免出现的粘结状况进行了分析,研究结果表明空洞的面积越大,芯片的温度越高.空洞位于拐角,即粘结区域四角的位置时,芯片散热情况最差.而在标准中给出的,芯片空洞面积达50%,且位于拐角时,芯片的温度最高.     

声测定位技术的现状研究

声测定位技术是利用声学与电子装置接收声信号以确定声源位置的一种技术,具有隐蔽性好、保密性强、不易受干扰等特点。近年来受到各国的重视,并在军事领域得到长足的发展。重点介绍声测定位的关键技术,时延估计算法和声测阵列的选择是影响定位精度的主要因素。对几种广泛采用的声测阵列,给出相应的基本原理、定位计算方法并对各自特点进行比较。在声测定位系统中,利用时延估计对声信号进行处理是定位的重要环节,介绍了时延估计的基本理论、研究状况以及精度分析和比较,分析了影响定位精度的其他因素。     

脉冲噪声环境下一种韧性的时延与 多普勒频移联合估计法

由于α稳定分布噪声会降低基于二阶循环统计量的传统方法的性能,本文基于分数低阶统计量理论提出p阶循环相关的概念并给出相应性质及证明,在此基础上对已有的循环模糊函数进行了广义化.计算机仿真表明,这种广义的循环模糊函数能够在高斯和α稳定分布噪声条件下有效地联合估计时延和多普勒频移,其性能不仅优于基于二阶循环相关的CCA(循环模糊函数)法,也优于FLOAF(分数低阶模糊函数)法,是韧性的、具有更广泛应用意义的方法.     

效率、功率因数及其关系的讨论

效率和功率因数是电气与电子工程中的两个重要参数.它们既是两个不同的概念,又有密切的联系.但在目前的电路分析及模拟电子技术的部分教材中,关于效率、功率因数及其关系问题仍然存在一些错误概念,或者对这些重要的问题言之甚少.本文针对上述问题作了详细地讨论.并通过一个例子分析了效率及功率因数之间的关系,纠正了对这些问题的模糊认识,使这些概念更加明确.笔者认为文中的分析和讨论对电类各专业的学生掌握这些基本问题是有益的.     

电子装备技术状态自动监测与可靠性分析系统

介绍了电子装备技术状态自动监测与可靠性分析系统的组成、主要功能、技术指标、特点和实现方法,以及应用情况和前景.     

Models of Restoration Probability in WDM Networks Employing Active Restoration

The ever-increasing demand for network bandwidth makes network survivability an issue of great concern. Lightpath restoration is a valuable approach to guaranteeing an acceptable level of survivability in WDM optical networks with better resource utilization than that of its protection counterpart. Active restoration (AR) is a newly proposed lightpath restoration scheme [M. Mostafa et al. OSA Journal of Optical Networking, vol. 3, no. 4, pp. 247–260] that combines the best of protection and reactive restoration while avoiding their shortcomings. In this paper, we conduct detailed performance analysis on the restoration probability of AR-based WDM networks. In particular, analytical models of restoration probability are developed respectively for networks with full-wavelength conversion capability and for networks without wavelength conversion capability under different backup path searching schemes. Based on the new models, we investigate the effects of wavelength availability, wavelength conversion capability, path length as well as backup path seeking methods on the restoration probability.     

Optical signal routing using emission packet positioning of semiconductor heterostructure

We present a novel optical switching technique utilizing emission packet positioning of semiconductor heterostructure. A modulation-doped p-AlGaAs-GaAs heterostructure is employed to control spontaneous emission packet positioning with electric fields. Emission packets generated by optical input signals are brought over 150 /spl mu/m with electric fields, so the output fibers can detect the emission intensity as signals. The first-order analysis indicates that the drift velocity of minority electrons in GaAs limits the detectable maximum data rate and nanoseconds timescale signal routing operation at 20 Gb/s is possible at an electron drift velocity of 2/spl times/10/sup 7/ cm/s.     

Research activities on next-generation mobile communications and services in Korea

In this article we present a perspective on next-generation mobile communications and services. As a preliminary research work on next-generation mobile communications, we exploit what next-generation mobile services will be (S. Ryu et al., May 2003). We define next-generation mobile services as a hierarchy of services consisting of three different service levels: the service areas, the service functionalities, and the service technologies. We derive these service levels by means of scenario-based analysis. Next we propose conceptual reference network architecture, focusing on the realization of the service technologies. We divide the network into four different parts: a user equipments and access part, a network service provisioning layer part, a network control layer part, and non-mobile network operator service pan, according to characteristics of information and service flows within a network. In this reference network architecture, service elements such as servers, processors, and gateways are placed in each network part to support the derived next-generation mobile services. Finally, we give a brief introduction of research and development activities for next-generation mobile communication systems and services in Korea.     

部分耗尽SOI体接触nMOS器件的关态击穿特性

分别采用具有硅化物和不具有硅化物的SOI工艺制成了部分耗尽SOI体接触nMOS晶体管.在体接触浮空和接地的条件下测量了器件的关态击穿特性.通过使用二维工艺器件模拟,并测量漏体结的击穿特性,详细讨论和分析了所制成器件击穿特性的差异和击穿机制.在此基础上,提出了一个提高PD-SOI体接触nMOS击穿特性的方法.     

双极晶体管△Vbe瞬态热阻测试法精度修正

对双极型晶体管△VBE瞬态热阻测试法中晶体管壳温波动和测量延迟时间的误差进行了分析,提出了提高测试精度的误差修正方法.以3DK457(F0金属封装)双极晶体管为实验对象进行了研究,结果表明:晶体管瞬态热阻△VBE修正测试方法与红外扫描热像法和标准电学法相比较在保持较高测量精度的前提下,测试成本低,测量效率高.