一种用于提取超大规模集成电路电容的新型库查找法

提出了八种节点电容典型结构用以建立电容模型库,并阐明了这八种结构可以提取大多数VLSI互连线的电容参数,给出了这些结构的拟合公式.采用该库查找法计算的互连线电容结果与FastCap所得结果非常吻合.由于电容是直接代入拟合公式计算得到的,所以计算速度非常快.     

双极型晶体管交流模型参数的优化提取

双极型晶体管交流模型参数的优化提取包括势垒电容模型参数和正向渡越时间模型参数的优化提取.采用非线性函数最小二乘法拟合实验曲线对上述参数的提取是非常有效的.电容模型公式是由耗尽层近似理论推得的.用该电容模型公式拟合实验曲线,得到了最优的电容模型参数,计算曲线与实验曲线的误差约为1％.为了精确模拟正向渡越时间,根据实验结果对 SPICE 2G程序中的模型公式进行了修正,用修正后的模型公式拟合实验曲线,得到了最优的描述正向渡越时间的模型参数,计算曲线与实验曲线的误差为1.02％.     

一种新型二分电容DAC的设计

为了进一步减小电容阵列DAC占用的面积,提出了一种可用于SAR ADCs的二分电容阵列(三段电容阵列,T-SC)结构。与传统二段电容阵列相比,提出的二分电容阵列在不增加对电容匹配性要求的前提下,减少了芯片面积。在理论上分析了该结构的电容失配和寄生效应,归纳提出了一种计算电容阵列DAC DNL的简易公式。Matlab仿真结果与理论分析有较好的一致性,三段电容阵列结构能够实现较好的二进制权重特性;根据提出的计算DNL的简易公式进行参数设计,仿真DNL标准偏差为0.51 LSB,与理论计算0.5 LSB相差0.01 LSB。     

缝隙波导谐振阵最大带宽分析方法研究

文中基于波导并联缝隙的RLC 串联等效电路,建立了谐振阵阻抗带宽的通用分析方法,对单一过载和 过载匹配两种设计条件下谐振阵的最大带宽进行了研究,给出了最优带宽拟合公式并确定了相应匹配条件下的导纳特 性,系统解决了谐振阵阻抗带宽的设计边界与设计方向问题。最后结合缝隙等效电路,提出了一种新颖的导纳特性调 整方法,通过引入平行隔栅控制缝隙导纳的电容特性,利用过载匹配技术实现了8 单元中心馈电谐振阵的最大带宽设 计。全波仿真结果显示,VSWR≤1. 5 时的最大带宽可达到16. 2%,相应的电容参数C 为4. 9 pF,该结果与拟合公式得 到的电容参数C 及最大带宽计算数据较为一致,并且缝隙归一化导纳特性的全波仿真数据与等效电路优化出的最佳 导纳特性的吻合性非常好。最后设计了一个8×8 试验阵并展开了测试,该试验阵VSWR≤1. 5 时的工作带宽为16. 4%, 与全波仿真结果及等效电路分析结果均较为一致,证明了文中提出的谐振阵的带宽分析方法是准确可行的。     

InP基HEMTs器件16参数小信号模型

针对InAlAs/InGaAs InP基 HEMTs提出了一种16参数小信号拓扑结构.拓扑结构中引入栅源电阻(Rgs)表征短栅沟间距引起的栅泄漏电流效应.另外还引入输出跨导(gds)和漏延迟(τds)描述漏端电压对沟道电流的影响以及漏源电容(Cds)引起的相位变化,从而提高了S22参数拟合精度.外围寄生参数通过open和short拓扑结构计算得出,本征部分利用去除外围寄生参数后的Y参数计算得出,最终模型参数值经过优化以达到最佳拟合状态而确定.结果表明,s参数和频率特性的仿真值与测试数据拟合程度很好,Rgs和τds的引入降低了模型误差.准确合适的InP基HEMTs小信号模型对于高频电路设计非常重要.     

模型参数对双极管差分对延时的影响

本文结合我们所开发的两种ＢｉＣＭＯＳ工艺，讨论了双极管模型参数对双极管差分对的影响．采用电荷控制法，推导得出了双极管差分对的延时公式．该公式物理意义明确直观，能清楚地解释双极管各模型参数、工作条件等因素对双极管差分对延时的影响，并能指导电路设计和工艺制造；最终公式中全部使用ＰＳＰＩＣＥ参数，便于计算；该公式虽然只讨论了三个电容（发射结电容、集电结电容和衬底结电容）、三个电阻（发射极电阻、集电极电阻、基极电阻）、正向渡越时间和正向电流放大倍数八个参数，但其计算结果与ＰＳＰＩＣＥ模拟结果呈现出良好的一致性．     

集成电容式传感器边界电极的静电电容值分析

 本文研究一种梳齿电极结构的集成电容式传感器,利用保角变换对其边界电极的静电电容值情况进行推导,给出了边界电极电容值的解析表达式,并利用Ansys软件对其进行仿真验证。结果显示解析公式得到的计算结果和软件仿真结果相吻合,说明得到的公式具有高的精度。利用所给的解析表达式可以为设计和应用该结构电容式传感器提供更好的理论基础。     

基于LTCC技术的垂直堆叠结构电容的设计

通过HFSS软件对基于LTCC技术的垂直堆叠结构的电容进行三维建模,利用ADS软件对等效电路进行拟合计算.设计出工作频率为1 GHz下有效电容值为30 pF的垂直堆叠结构电容.通过分析电容的结构参数对有效电容和品质因数的影响可知,增加电容值可以通过增加介质的相对介电常数、极板面积等来实现,这对埋置电容设计和调试具有理论...     

一种简化的片上螺旋电感双π等效电路模型

提出了一种简化的片上螺旋电感双π等效电路模型。该模型可有效的反映螺旋电感中的趋肤效应、邻近效应、衬底耦合、馈通电容、导体间电容等分布效应的影响。推导了该模型中元件的估算公式。由该估算公式得出的元件参数，可作为与实际数据拟合的参考值，从而提高了拟合的效率与准确性。经拟合后的等效电路模型，在0．1～10GHz范围内，与电磁场仿真软件(ADS momentum)所得的仿真结果有很好的一致性。     

InP基HEMTs器件16参数小信号模型（英文）

针对InAlAs/InGaAsInP基HEMTs提出了一种16参数小信号拓扑结构.拓扑结构中引入栅源电阻(R_(gs))表征短栅沟间距引起的栅泄漏电流效应.另外还引入输出跨导(gds)和漏延迟(τ_(ds))描述漏端电压对沟道电流的影响以及漏源电容(C_(ds))引起的相位变化,从而提高了S_(22)参数拟合精度.外围寄生参数通过open和short拓扑结构计算得出,本征部分利用去除外围寄生参数后的Y参数计算得出,最终模型参数值经过优化以达到最佳拟合状态而确定.结果表明,s参数和频率特性的仿真值与测试数据拟合程度很好,R_(gs)和τ_(ds)的引入降低了模型误差.准确合适的InP基HEMTs小信号模型对于高频电路设计非常重要.     

基于Simulink的雷达方位转台伺服系统闭环仿真

介绍了在Matlab的Simulink仿真环境下建立雷达方位转台伺服系统仿真模型。具体介绍了机电系统的仿真模型,并引入了对旋转系统有重要影响的摩擦力矩模型,建立了两种类型的雷达转台伺服系统闭环仿真模型,并给出了部分仿真结果。     

Semi-numerical modelling of an n-channel irradiated MOSFET

A semi-numerical model of a metal-oxide-semiconductor field effect transistor (MOSFET) has been developed for theoretical examination of the effect of ionizing radiation on the characteristics of the device. The present model utilizes the radiation-induced changes in the flat-band voltage to estimate the change in the surface charge carrier concentration which in turn changes the mobility of the surface channel and affects the source-to-drain current. For the first time a model of an irradiated MOSFET has been presented that incorporates the effect of both transverse and longitudinal electric fields in the transport of the carriers in the surface channel. The present model can also be used to determine the characteristics of the device in the pre-irradiated condition. The validity of the model has been established by comparing and contrasting the results in the preirradiated condition with those obtained using other models, including twodimensional models. The results obtained on the basis of our model are compared with reported experimental results and also a SPICE (Level 3) model in the post-irradiated condition. It is found that our model gives a better fit to the reported experimental results as compared with SPICE models.-The present model is expected to yield fairly accurate results for estimation of I _D V _D characteristics and the transfer characteristics, even for a short channel device.     

多径非相关瑞利信道生成的改进

提出一种多径非相关瑞利信道生成改进方法。和目前其他瑞利信道生成方法相比，该方法不仅能满足瑞利信道所具备的统计特性，而且保证信号多径传播中各径信号不相关特性。通过仿真可以看出该方法的单径信道二阶特性和现有模型统计特性相仿，而多径非相关性明显较好。     

Performance modeling of MPEG‐4 video streaming over IEEE 802.11 using distribution coordination function

Delivering video streaming over wireless Internet is becoming increasingly popular. However, most of the research studies focused on the modeling analysis of system performance such as saturation throughput and channel utilization. Perceived quality of video streaming cannot be assessed solely based on the results of analytical models. In this paper, we propose a model to assess the perceived quality of MPEG‐4 video streaming over IEEE 802.11 distribution coordination function (DCF)‐based wireless local area networks. The analysis of our proposed model considers not only effects of losses such as collision loss from channel access competition but also wireless loss caused by wireless interferences. Moreover, the impact of the loss of specific MPEG‐4 video frames is also taken into account in the performance analysis. The model was validated by comparing our performance results with results obtained from simulation and analytical models. The results show that our proposed model is able to predict the perceived quality of MPEG‐4 video streaming over DCF‐based WLAN more accurately than other models. Copyright © 2010 John Wiley & Sons, Ltd.     

PDP驱动芯片中高压LDMOS建模

建立了PDP驱动芯片用高压LDMOS的SPICE子电路模型,该模型集成了LDMOS固有特性：准饱和特性、电压控漂移区电阻、自热效应、密勒电容等. 与其他物理模型和子电路模型比较,该模型不但能提供准确的模拟结果,而且建模简单快捷,另外该模型可较容易地嵌入SPICE模拟软件中. 模型的实际应用结果显示：模拟与实测结果误差在5%以内.     

PDP驱动芯片中高压LDMOS建模

建立了PDP驱动芯片用高压LDMOS的SPICE子电路模型,该模型集成了LDMoS固有特性:准饱和特性、电压控漂移区电阻、自热效应、密勒电容等.与其他物理模型和子电路模型比较,该模型不但能提供准确的模拟结果,而且建模简单快捷,另外该模型可较容易地嵌入SPICE模拟软件中.模型的实际应用结果显示:模拟与实测结果误差在5%以内.     

Attribute data reliability decay models

The problem of estimating the reliability of a decaying system is considered. Several models are developed for providing reliability estimates when attribute (success, failure) sampling data over m stages indicates decreasing system reliability. An ordered maximum likelihood estimate model (MLE) is developed which provides decaying system reliability estimates under reliability order restrictions. A second classical model is an adaptation of the standard cumulative maximum likelihood estimate (mle) model. The model uses a weighting factor such that more current test information is weighted more heavily than is earlier data.Computer simulation trials were then conducted to compare the performance of the models with the standard cumulative MLE and binomial MLE models. The ordered MLE model is shown to yield the best results, performing even better than the binomial MLE model. The ordered MLE model produces generally conservative estimates of system reliability. The ordered MLE model also produces less error in its estimates than the binomial MLE model, both in terms of root mean squared error and standard deviation. Larger sample sizes are shown to yield the best results for both the binomial and ordered MLE models. While the ordered MLE model outperforms the binomial MLE model at every stage for sample sizes of 20 and 40, it is shown that the ordered MLE model offers significant improvement over the binomial MLE model for sample sizes of twenty.     

Analysis of a three-dimensional dielectric mixture with finitedifference method

The present paper reports the results of a numerical analysis of electric fields in random dielectric materials. The effective permittivity of a three-dimensional (3D) dielectric mixture is calculated by the finite difference method. The results show the distribution of the effective permittivity of a mixture with different random inclusion positionings. New empirical mixing models are created as least squares approximations to fit the collection of numerical results. The calculated permittivity distribution is also compared with theoretical mixture models, showing that in case of clustered inclusions, the Bruggeman model is quite reasonable. On the other hand, if the inclusions in the mixture are separate, the results are closer to the Maxwell-Garnett model     

融合内容表示的度量排序学习推荐模型

融合内容语义信息的推荐模型可以有效缓解音乐推荐系统中的数据稀疏性和冷启动问题.然而,这些模型是通过最小化预测评分误差学习用户与音乐的全局关系,忽略了用户和音乐隐式特征的细粒度差异.此外,内容语义特征是以推荐任务无关的无监督学习方式提取的,从而导致不精确推荐.为此,本文提出了融合内容表示的度量排序学习推荐模型,该模型是以个性化排序最优化为目标的概率图模型,利用度量学习从全局和细粒度层面挖掘用户音乐偏好.为了解决冷启动推荐问题,本文建立了与推荐任务相关的监督学习策略训练内容语义特征提取模型.在KKBOX和MIGU数据集上的实验结果表明,提出的模型显著提升了冷启动音乐推荐的效果,在不同稀疏度数据集上的鲁棒性得到了显著增强.     

Flip chip on board solder joint reliability analysis using 2-D and3-D FEA models

This study investigates the effects of employing different two-dimensional (2-D) and three-dimensional (3-D) finite element analysis (FEA) models for analyzing the solder joint reliability performance of a flip chip on board assembly. The FEA models investigated were the 2-D-plane strain, 2-D-plane stress, 3-D-1/8th symmetry and 3-D-strip models. The different stress and strain responses generated by the four different FEA models were applied to various solder joint low cycle fatigue life prediction relationships. The investigation shows that the 2-D-plane strain and 2-D-plane stress models gave the highest and lowest solder joint strains, respectively. The 3-D-strip and 3-D-1/8th symmetry model results fall in between the 2-D-plane strain and 2-D-plane stress model results. The 3-D-1/8th symmetry model agrees better with the 2-D-plane strain model, while the 3-D-strip model agrees better with the 2-D-plane stress model results. The results for the fatigue life prediction analyses also show similar trends