矩量法分析屏蔽导体内的多层介质多导体传输线

利用矩量法分析屏蔽导体内的多层介质多导体传输线。首先，建立该问题的算子方程；然后离散化算子方程，通过对导体和介质分界面的总电荷及介质和介质分界面自由电荷的自由空间二维格林函数分析，得出矩阵方程；最后得出屏蔽导体内多层介质中各导体的电容矩阵和电感矩阵。数值结果与现有类似结构分析结果相比较一致性较好。     

多层介质多导体传输线的小波矩量法分析

全电荷格林函数法是解决分层介质的多导体传榆线的参数提取的一个通用有效的方法，但是用矩量法处理时需将导体表面和介质分界面一起剖分，系数矩阵的阶数较大，计算效率降低。详细分析了多层介质多导体传榆线，并在矩量法处理时引入小波变换，使原稠密系数矩阵变换为稀疏矩阵。从而提高了求解速度。     

静电屏蔽问题中的部分电容与电场耦合

本文以导体屏蔽壳、壳外导体、壳内导体及参考导体(大地)构成的4导体静电独立系统为例,详细分析了其电位系数、感应系数及部分电容的取值特性。结果表明,无论屏蔽壳体是否接地,壳外导体与壳内导体的互有部分电容均为零;屏蔽壳体不接地时,内外导体之间存在电场耦合;屏蔽壳体接地后,内外导体之间不存在电场耦合。     

考虑导体厚度的微带结构计算方法研究

本文主要研究考虑导体厚度的三维微带结构,使用若干个零厚度导体去模拟厚导体,为了减少计算量和简化计算方法,用复镜象表示格林函数,Ｃｈｅｂｙｓｈｅｖ多项式表示电荷密度,通过伽略金方法把求解方程变为矩阵方程,计算电容系数。本文结果与已知结果比较,发现此法对三维厚导体板结构进行模拟较简单明了,精度足够,占用ＣＰＵ时间也较少。     

“电磁场”课程中部分电容的实验方法讨论

部分电容实验是本科生＂电磁场＂课程静电场部分的主要实验之一。本文总结了部分电容实验中两种测量方法———直接法和间接法,并给出了部分参数的测量电路图;笔者分析了学生使用检流计测多导体静电独立系统中某一个导体上的电荷时易犯错误的原因,并给出正确的做法。     

一种提取多层介质多导体互连电磁参数的快速算法：有限差分－不变性测试方程法

本文首次利用ＭＥＩ方法计算了多层介质多导体互连的电容和电感矩阵．由于引入了测试环的概念，避免了多层结构的格林函数的推导和Ｓｏｍｍｅｒｆｅｌｄ积分的计算，同时也去掉了传统ＭＥＩ方法中ＭＥＩ系数与几何形状有关的假设．计算结果表明：本文提出的算法正确，与常见的算法如矩量法，边界元法和有限元法等方法相比，计算速度大大加快，并且对结构的适应性强，可以分析截面为任意形状且导体有耗的互连，因此该方法是一种提取电磁参数的快速算法．在计算得到的电容和电感矩阵的基础上，本文还利用双重波形收敛法计算了端接非线性负载的多导体互连各端口的瞬态响应．     

多导体系统分布电容矩阵的空域格林函数

提出一种计算多导体系统中分布电容矩阵的简单有效方法。该方法适用于无限薄带条的多导体系统,用矩量法和谱域格林函数求取空域格林函数的表达式,再解电容矩阵。     

电容电荷守恒和电感磁链守恒的条件

动态电路换路时，若存在由纯电容和理想电压源构成的回路，则电容电压就有可能跃变，在含电压可能跃变的电容支路的割集中，若除电容支路外的支路中无冲激电流存在，则电容电荷守恒，否则电容电荷有可能不守恒；若存在由纯电感和理想电流源构成的割集，则电感电流就有可能跃变，在含电流可能跃变的电感支路的回路中，若除电感支路外的支路中无冲激电压存在，则电感磁链守恒，否则电感磁链有可能不守恒。文中同时给出了电容电荷不守恒和电感磁链不守恒时电路初始条件的求解方法。     

基于全电荷格林函数的MEI方法在超高速集成电路互连线参数提取中的…

本文提出了将全电荷格林函数用于测度不变方程法中，即将全电荷格林函数代替完全格林函数积分以求得测量函数从而决定测度不变方程。并以这种ＭＥＩ法计算了某些多导体互连线的分布电容矩阵。     

基于全电荷格林函数的MEI方法在超高速集成电路互连线参数提取中的应用

本文提出了将全电荷格林函数用于测度不变方程（ＭＥＩ）法中，即将全电荷格林函数代替完全格林函数积分以求得测量函数从而决定测度不变方程．并以这种ＭＥＩ法计算了某些多导体互连线的分布电容矩阵．     

A new charge conserving capacitance model for GaAs MESFET's

We present a new charge conserving capacitance model for Gallium-Arsenide (GaAs) metal semiconductor field effect transistors (MESFET's) based on the quasi-static approximation and a proper partitioning of the channel charge between the source and the drain terminals. A total of nine so-called transcapacitances were determined by taking derivatives of the various terminal charges with respect to the voltages at source, drain, and gate. The transcapacitances are nonreciprocal, i.e., C_ij≠C_ji when i≠j, and can be organized in a 3×3 matrix incorporating Kirchhoff's current law (charge conservation) and independence of reference. The present capacitance model is valid both above and below threshold, and shows good agreement with experimental data over a wide range of gate and drain biases. The model is analytical and suitable for implementation in circuit simulators     

TOM3 capacitance model: linking large- and small-signal MESFETmodels in SPICE

Improved accuracy in the modeled gate capacitance of GaAs metal-semiconductor field-effect transistors (MESFET's) is obtained in SPICE using conservation of charge in an implanted layer. The gate junction creates a natural partition between mobile and fixed channel charges. Relating the gate charge to the channel current creates gate capacitances dependent upon the channel current derivatives linking the small-signal model to the large-signal equations. Results are illustrated using a depletion-mode MESFET     

静态场部分电容和互感的测量

多导体部分电容和互感是静态场中非常重要的两个概念.本文介绍了部分电容和互感的特性及测量原理,给出一种测试仪器,通过对具体参数的测试,所得的测试结果与理论计算结果相吻合.实践表明,两个实验系统的开发不仅可以促进学生综合运用所学知识的能力,也可激发学生对电磁场专业理论知识学习的兴趣.     

A coupled-mode theory for multiwaveguide systems satisfying the reciprocity theorem and power conservation

Two sets of coupled-mode equations for multiwaveguide systems are derived using a generalized reciprocity relation; one set for a lossless system and the other for a general lossy or lossless system. The second set of equations also reduces to those of the first set in the lossless case under the condition that the transverse field components are chosen to be real. Analytical relations between the coupling coefficients are shown and applied to the coupling of mode equations. It is shown analytically that our results satisfy exactly both the reciprocity theorem and power conservation. New orthogonal relations between the supermodes are derived in matrix form with the overlap integrals taken into account.     

Analytic approximation for open-end capacitance in symmetriccoplanar-strip waveguides

Conformal mapping and the partial capacitance technique are used to derive simple and accurate closed form approximations for the open-end capacitance in a symmetric coplanar-strip waveguide     

A model for the capacitance—Voltage characteristics of MODFET's

Using Fermi-Dirac statistics, a model for the gate capacitance-voltage characteristics of MODFET's is developed that includes not only the capacitance component due to two-dimensional electron gas density but also the capacitance component due to donor neutralization. To analytically solve Poisson's equation with the Fermi-Dirac statistics, we analyzed the theory by using two regions (the complete ionization region and the partial ionization region of doped impurities). Using the obtained C-V relationships, the gate capacitance is calculated with the numerical calculation method. The results are in good agreement with experimental data.     

液晶的粘滞系数及其测定

介绍向列相液晶的各个粘滞系数，包括体积粘滞系数、运动粘滞系数、平动粘滞系数（Ｍｉｅｓｏｗｉｃｚ系数）、转动（扭曲）粘滞系数、Ｌｅｓｌｉｅ系数等及其粘度计和磁场的测量方法。     

IGBT negative gate capacitance and related instability effects

For high collector voltages, Insulated Gate Bipolar Transistors (IGBTs) exhibit a negative gate capacitance. In this condition, a p-channel inversion layer is formed on the N-base surface. The positive charges in the p-channel induce negative charges in the MOS gate electrode. This results in a negative gate capacitance. As a consequence of this negative capacitance, IGBT operation is inherently unstable, leading to current redistribution between cells or even chips     

Challenges in SiC power MOSFET design

The impact of fundamental and technological parameters is considered for SiC power MOSFETs. The wide bandgap nature of SiC increases the surface electric field by 2× at inversion compared to silicon, placing an important role on surface roughness in reducing the field-effect mobility. The presence of interface-trapped charges also acts to reduce the channel mobility and increases the sensitivity of the threshold voltage to temperature. The high critical electric field of SiC increases the stored energy in the switch output capacitance by 10× compared to silicon. For hard-switched converters, it is important to design SiC MOSFETs with a high saturation current to enable high-speed turn-on transients required to discharge the integral drain-source capacitance.