电迁移物理模型参数统计特性提取新方法

随着ＶＬＳＩ技术的发展，电迁移已成为集成电路最主要的失效原因之一，其可靠性评估技术也显得愈加重要。要改进该技术，不仅需要确定可靠性物理模型参数，而且要求掌握参数的统计分布特性。基于电迁移物理模型，提出一种提取参数统计分布特性的新方法。与传统方法相比，此方法不仅所需实验样品少、实验次数少，能真正得到反映样品离散性的物理模型参数的统计分布特性，而且也可用于其它失效机理（如栅氧击穿）物理模型中。     

PSPICE程序使用功能的扩展

介绍了集成电路模拟程序ＰＳＰＩＣＥ的几种特殊功能，包括利用ＰＳＰＩＣＥ程序求取电路的Ｓ参数，电路的噪声系数以及建立电路器件宏模型等。     

PSPICE程序使用功能的扩展

介绍了集成电路模拟程序ＰＳＰＩＣＥ的几种特殊功能，包括利用ＰＳＰＩＣＥ程序求取的Ｓ参数，电路的噪声系数以及建立电路器件宏模型等。     

多晶硅发射极晶体管（PET）Gummel－Poon模型

本文建立了能直接用于ＳＰＩＣＥ电路分析程序中的ＰＥＴ－ＧＰ模型。研究表明：可以采用两种方法来使用ＰＥＴ－ＧＰ模型。本文利用所研究器件的结构参数计算了ＰＥＴ－ＧＰ模型参数β＿Ｆ和特征频率ｆ＿Ｔ，ｆ＿Ｔ的计算和实验结果符合较好。β＿Ｆ的计算表明，所研究器件的多晶硅／硅界面复合较强，复合速度Ｓ＿ｐ达到１０￣６ｃｍ／ｓ。     

多晶硅发射极晶体管（PEI）Gummel—Poon模型

本文建立了能直接用于ＳＰＩＣＥ电路分析程序中的ＰＥＴ－ＧＰ模型。研究表明：可以采用两种方法来使用ＰＥＴ－ＧＰ模型。本文利用所研究器件的结构参数计算了ＰＥＴ－ＧＰ模型参数βＦ和特征频率ｆＴ。ｆＴ的计算和实验结果符合较好。βＦ的计算表明，所研究器件的多晶硅／硅界面复合较强，复合速度ＳＰ达到１０＾６ｃｍ／ｓ。     

微波MESFET小信号噪声等效电路模型分析

本文将噪声源引入ＭＥＳＦＥＴ小信号等放电路模型，推导了由ＭＥＳＦＥＴ内部参数计算其参数的计算公式及由噪声源引起的各端口噪声电流表达式和噪声参数的计算公式，编制了相应的计算程序和绘图程序，经验证得到了令人满意的结果，说明ＭＥＳＦＥＴ小信号噪声等效电路模型对研究和应用ＭＥＳＦＥＴ是有效的和新颖的。     

利用PSPICE实现数字模拟电路的混合模拟

ＰＳＰＩＣＥ是一种能够数字模拟电路的混合模拟电子线路ＣＡＤ软件，文中讲述了ＰＳＰＩＣＥ的描述语言，使用方法，模型与参数，并讨论了ＰＳＰＩＣＥ的优势与不足。     

偏置相关GaAs MESFET建模分析

通过对利用多组偏置条件下的Ｓ参数获得精确ＧａＡｓ ＭＥＳＦＥＴ器件非线性模型方法的讨论，提出了新的沟道电流的栅电容模型，并提取了ＤＣ和电容模型参数。实验结果表明该模型模拟值和测量值吻合很好。     

高速互连线CAD技术研究

采用边界积分方程结合矩量法计算高速第连线电磁参数，讨论了版图关键互边线提取技术和互连的ＳＰＩＣＥ模型建立技术，并用ＳＰＩＣＥ简要分析了互连线效应。     

偏置相关GaAs MESFET建模分析

通过对利用多组偏置条件下的Ｓ参数获得精确ＡａＡｓＭＥＳＰＥＴ器件非线性模型方法的讨论，提出了新的沟道电流和栅电容模型，并提取了ＤＣ和电容模型参数。实验结果表明该模型模拟值和测量值吻合很好。     

目标表面BRDF统计建模中的遗传模拟退火算法

结合基本遗传算法与模拟退火算法,构造出了新的具有全局搜索优化特性的遗传模拟退火算法.根据卫星表面BRDF实验数据和统计模型,引用遗传模拟退火算法,获得样片BRDF模型参数的优化估计,从而获得了三维空间的BRDF分布,其优化参数后的模型在另一部分数据上也得到了很好的吻合验证.     

Approaches for reliability modeling of continuous-state devices

Three approaches for reliability modelling of continuous state devices are presented in this paper. One uses the random process to fit model parameters of a statistical distribution as functions of time. This approach allows the data set to be from any general distribution. The second approach uses the general path model to fit parameters of the model as functions of time. The relationship between the random process model and the general path model is illustrated. The third approach uses multiple linear regression to fit the distribution of lifetime directly. This approach has less restriction on the degradation data to be analyzed. All three approaches are illustrated with examples. Finally a mixture model is proposed which can be used to model both catastrophic failures and degradation failures. This mixture model also shows engineers how to design experiments to collect both hard failure data and soft failure data. Topics for further investigation in continuous device reliability modelling include further investigation of the mixture model, application of these models to practical situations, and using complex statistical distributions to fit degradation data     

电离辐射前后双极型晶体管统计特性

双极型晶体管性能统计分布在电离辐射之后会发生变化,从辐射前对称的正态分布转化为辐射后非对称的对数正态分布,这一统计特性转化缺乏清晰的物理图像。为了从微观机理层次解释这一转化过程,通过大样本定制晶体管电离辐射效应实验,获得基极电流、界面陷阱电荷辐射前后的统计特性,发现两者统计特性转化具有一致性。基于基极电流的解析物理模型分析发现辐射前后基极电流统计特性转化源自于界面陷阱电荷统计特性转化,并基于中心极限定理给出了界面陷阱电荷辐射前后统计特性转化的物理解释,即界面缺陷面密度的分散性转化源于多个随机变量以乘积形式实现界面缺陷物理过程。     

X波段小擦地角海杂波WW分布建模

为了更好地描述X波段小擦地角海杂波建模中出现的重拖尾现象,研究WW分布建模方法及其统计特性,进而改善统计分布模型对海杂波数据的拟合效果。基于X波段海杂波实测数据,分析在不同海况和极化方式下两重韦布尔(WW)分布对海杂波实测数据的拟合效果。通过其与韦布尔分布、对数正态分布、K分布等统计分布模型拟合优度检验的对比,表明WW分布可以很好地拟合具有重拖尾现象的海杂波数据。此外,WW分布能够在不同极化域内准确地描述海杂波的统计特性,具有较好的海杂波幅度分布统计建模能力。     

Compound representation of high resolution sea clutter

A proposed form of compound distribution to describe the non-Rayleigh distribution and correlation properties of high resolution radar sea clutter is shown to be a good fit to experimental data. From this model the K distribution is derived, and a possible physical mechanism is discussed.     

A multiscale model for MPEG-4 varied bit rate video traffic

This paper studies modeling approach of MPEG-4 VBR video traffic based on multifractal multiplicative model. Multiscale analysis reveals that the multiplier distribution is different in style on different time scales. Based on statistical characteristics of the multipliers, a composite modeling approach is proposed: Gaussian distribution is used to fit multiplier distribution at large time scales, a new statistical distribution-Symmetric Pareto distribution to fit multiplier distribution at small time scales and a linear model to model frame traffic. Simulations are performed to validate the good effect of this approach.     

A statistical model for the factory radio channel

A statistical model, based on experimental data, is presented to characterize the multipath propagation medium in typical manufacturing environments. The statistical behavior of the medium is described by a time-varying impulse response which includes the distribution of the parameters of the channel such as the gain, the interarrival time, and the number of paths. The resolvable components in a number of experimentally measured pulse responses of indoor factory radio channels were used to estimate the channel statistics. The interarrival times of the signals were modeled by the Weibull distribution. A model for the distribution of signals was presented using the modified beta distribution. The path gain coefficients were represented using the Rayleigh, Rician, or log-normal distributions. The model for the factory channel is flexible enough to fit the data for other indoor sites by changing the parameters of the factory channel appropriately relative to the size, topography, and other structural features of the site     

某型光电探测系统可靠性增长评估

光电探测系统研制阶段的试验数据具有小样本特征,针对传统的可靠性评估结果偏保守的问题,基于单调约束模型,通过综合利用光电探测系统多阶段试验数据进行可靠性评估,以达到精确评估的目的。考虑将研制过程中不同试验阶段数据中包含的可靠性增长信息作为约束条件,推导出可靠度分布函数表达式,并给出一种等效的统计抽样计算方法——Monte Carlo模拟算法,使计算过程更加简便,便于工程应用。最后以某型光电探测系统为例,表明利用可靠性增长信息进行可靠性评估,可有效提高评估的精度。     

Empirical Statistical Model for LTE Downlink Channel Occupancy

This paper develops an empirical statistical channel occupancy model for downlink long-term evolution (LTE) cellular systems. The model is based on statistical distributions mixtures for the holding times of the channels. Moreover, statistical distribution of the time when the channels are free is also considered. The data is obtained through an extensive measurement campaign performed in Stockholm, Sweden. Two types of mixtures are considered, namely, exponential and log-normal distributions to fit the measurement findings. The log-likelihood of both mixtures is used as a quantitative measure of the goodness of fit. Moreover, finding the optimal number of linearly combined distributions using the Akaike information criterion is investigated. The results show that good fitting can be obtained by using either exponential or log-normal distributions mixture. Even though, the fitting is done for a representative case with a tempo-spatial consideration, the model is yet applicable in general for LTE and other cellular systems in a wider sense.

     

Multivariate statistical modeling for image denoising using wavelet transforms

Recently a variety of efficient image denoising methods using wavelet transforms have been proposed by many researchers. In this paper, we derive the general estimation rule in the wavelet domain to obtain the denoised coefficients from the noisy image based on the multivariate statistical theory. The multivariate distributions of the original clean image can be estimated empirically from a sample image set. We define a parametric multivariate generalized Gaussian distribution (MGGD) model which closely fits the sample distribution. Multivariate model makes it possible to exploit the dependency between the estimated wavelet coefficients and their neighbours or other coefficients in different subbands. Also it can be shown that some of the existing methods based on statistical modeling are subsets of our multivariate approach. Our method could achieve high quality image denoising. Among the existing image denoising methods using the same type of wavelet (Daubechies 8) filter, our results produce the highest peak signal-to-noise ratio (PSNR).