BME0402微型片式多层陶瓷电容器通过鉴定

由深圳市宇阳科技发展有限公司推出的贱金属电极材料体系（BME）0402规格微型片式多层陶瓷电容器（MLCC），于10月13日通过技术鉴定，实现了IT与通信终端产品在高品质MLCC元器件上的国内配套。当前MLCC技术的发展趋势突出表现在微型化、低成本贱金属化、高比体积电容量和高可靠性等方面。深圳市宇阳科技发展有限公司采用抗还原陶瓷介质与Ni、Cu电极组成的贱金属电极（BME）材料体系技术最新研制成功的微型MLCC（包括0402、0603等尺寸规格）达到国际先进标准水平，主要技术指标符合美国国家标准及电子工业协会标准ANSI/EIA-198…     

多层陶瓷电容器的失效分析

采用外观观察和金相分析方法,对绝缘电阻偏低的多层陶瓷电容器(MLCC,简称为C1)、以及无容值且端电极短路的MLCC(简称为C2),进行了失效原因分析,研究了这两种MLCC的失效机理。结果表明:C1的失效是因电路板过度弯曲使电容器受到过大的机械应力,以致C1内部产生裂纹;C2的失效是因额定电压为500 V,耐压不足而致电压击穿,产生瞬间高压裂纹。生产过程中避免电路板弯曲及选用匹配的电容器,可有效降低MLCC的失效率。     

带有耦合电容的多层陶瓷带通滤波器

提出一种抽头式阶梯阻抗带通滤波器。通过在谐振器开路端引入耦合电容，增强了两个揩振器之间的耦合，从而使通带变宽，通带内衰减也变小了。因此，在不改变体积的情况下，性能比以前更好。文中采用时域有限差分方法分析这种滤波器。     

Modeling and efficient handling of handoffs in integrated wireless mobile networks

We propose and analyze two handoff schemes without and with preemptive priority procedures for integrated wireless mobile networks. We categorize the service calls into four different types, namely, originating voice calls, originating data calls, voice handoff request calls, and data handoff request calls and we assume two separate queues for two handoff services. A number of channels in each cell are reserved exclusively for handoff request calls. Out of these channels, few are reserved exclusively for voice handoff request calls. The remaining channels are shared by both originating and handoff request calls. In the preemptive priority scheme, higher priority is given to voice handoff request calls over data handoff request calls and can preempt data service to the queue if, upon arrival, a voice handoff request finds no free channels. We model the system by a three-dimensional Markov chain and compute the system performance in terms of blocking probability of originating calls, forced termination probability of voice handoff request calls, and average transmission delay of data calls. It is observed that forced termination probability of voice handoff request calls can be decreased by increasing the number of reserved channels. On the other hand, as a data handoff request can be transferred from a queue of one base station to another, there is no packet loss of data handoff except for a negligibly small blocking probability.     

多层瓷介电容器失效模式和机理

系统介绍了开路、短路和电参数漂移这三种主要的MLCC失效模式,以及介质层内空洞和电极结瘤、介质层分层、热应力和机械应力引起介质层裂纹、其他微观机理等五种主要的失效机理。针对MLCC的失效分析技术,从生产工艺和使用设计上提出了预防MLCC失效的措施。     

无机介质集成薄膜电容的制备研究

以Cr/Ag/Cr金属膜系为电极,电子束蒸发镁橄榄石(2MgO·SiO2)膜为绝缘介质,在陶瓷基片(表面较粗糙)上制备了MIM结构无机集成薄膜电容。光学显微镜和扫描电镜分析显示,电容的绝缘强度和介电性能主要取决于介质膜致密程度。沉积后适当的热处理有助于改善电容性能,但过度的热处理却可能导致由晶化和扩散引起的负面作用。所得电容击穿场强达到了107V/m以上,5MHz频率tanδ为0.01。     

DCF型交流圆片瓷介电容器

通过对陶瓷介质、导体浆料、包封料等材料的选择，以及陶瓷介质厚度、被银瓷片留边量的设计，采用干压成型法成型，控制生坯密度为３．６２～３．９０ｇ／ｃｍ３，研制成功了额定电压为ＡＣ２５０Ｖ、ＡＣ４００Ｖ的ＤＣＦ型交流瓷介电容器。该产品已取得ＣＣＥＥ、ＵＬ、ＶＤＥ和ＣＳＡ安全认证。     

High-Q poly-to-poly capacitor for RF integrated circuits

A very high-Q poly-to-poly capacitor structure is proposed and measurement results are presented. The poly-to-poly capacitor is designed using a conventional 0.35 μm CMOS process. By optimising the design a Q-factor of >120 is obtained at 2 GHz     

Modeling gait transitions of quadrupeds and their generalization with CMAC neural networks

In this paper, two gait transition models of a quadruped are derived based on gait kinematics. The learning and generalization capability of the cerebellar model articulation controller (CMAC) neural network in learning gait transitions is then studied. The two gait transition models are the transition between two general periodic gaits and the transition between a periodic gait and a continuous follow-the-leader (FTL) gait, while maintaining FTL mode during the transition. These models are nonlinear and require either heuristic rules or simultaneous solution of several nonlinear equations. Many transition gaits are then generated by these kinematic gait transition models under various gait conditions and evaluated in terms of stability and smoothness of leg movements. The CMAC neural network is then applied to learn the good transition gaits in four transition conditions: (1) from wave gait to wave gait; (2) from wave gait to FTL gait; (3) from walk to trot; and (4) from trot to transverse gallop. The learning and generalization capability of the trained CMAC neural network is evaluated and found to be satisfactory. This study has demonstrated the potential of applying neural networks to learn walking machine gaits and gait transitions.     

Modeling of capacitor impedance in switching converters

Switched capacitor (SC) converters are gaining acceptance as alternatives to traditional, inductor-based switching power converters. Proper design of SC converters requires an understanding of all loss sources and their impacts on circuit operation. In the present work, an equivalent resistance method is developed for analysis, and equivalent resistance formulae are presented for various modes of operation. Quasiresonant converters are explored and compared to standard SC converters. Comparisons to inductor-based switching power converters are made. A number of capacitor technologies are evaluated and compared for applications to both SC converters and inductor-based converters. The resulting model can be used to accurately predict and optimize converter performance in the design phase.     

CT47型脉冲功率高压陶瓷电容器性能

基于材料和工艺特点,对新研锆钛酸钡基CT47型脉冲功率电容器的高压脉冲放电性能和贮存性能进行了分析,并根据脉冲功率应用场景设计了系列化性能研究实验。实验结果表明,该电容器温度特性良好,高压脉冲放电性能稳定,耐压值高,绝缘性能好,为该电容器在脉冲功率领域的应用奠定了良好的基础。     

Multilayer ceramic capacitor with ultra-low ESL for high-frequency decoupling applications

A novel multilayer ceramic capacitor is proposed using vertically oriented internal electrodes. Because this distinctive internal electrode configuration effectively reduces the current loop area in the device, the proposed capacitor provides ultra-low equivalent series inductance of 47.0 pH on average from a series resonant frequency to 3.0 GHz despite its relatively simple terminal structure. This excellent behaviour is both numerically and experimentally validated.     

High-pass realization of equal-valued capacitor active RC networks

The design of the Huelsman equal-valued capacitor network is extended to the case of a high-pass Butterworth characteristic. Special reference is made to the most suitable designs from a fabrication viewpoint.     

Fuzzy/neural congestion control for integrated voice and dataDS-CDMA/FRMA cellular networks

The paper proposes congestion control using fuzzy/neural techniques for integrated voice and data direct-sequence code division multiple access/frame reservation multiple access (DS-CDMA/FRMA) cellular networks. The fuzzy/neural congestion controller is constituted by a pipeline recurrent neural network (PRNN) interference predictor, a fuzzy performance indicator, and a fuzzy/neural access probability controller. It regulates the traffic input to the integrated voice and data DS-CDMA/FRMA cellular system by determining proper access probabilities for users so that congestion can be avoided and the throughput can be maximized. Simulation results show that the DS-CDMA/FRMA fuzzy/neural congestion controllers perform better than conventional DS-CDMA/PRMA with channel access function in terms of voice packet dropping ratio, corruption ratio, and utilization. In addition, the neural congestion controller outperforms the fuzzy congestion controller     

Modeling and sensitivity analysis of circuit parameters for flip-chip interconnects using neural networks

This paper presents a neural network-based technique for modeling and analyzing the electrical performance of flip-chip transitions. A lumped element model using a simple pi equivalent circuit is used to characterize the electrical properties of the flip-chip bond. Statistical experimental design is used to extract the electrical parameters for flip-chip characterization from measurements and full-wave simulations up to 35 GHz. The extracted data is used to train back-propagation neural networks to obtain an accurate model of the pi equivalent circuit components and s-parameters as a function of layout parameters. The prediction error of the models is less than 5%. The models are used to obtain response surfaces for the entire range of variation of layout parameters. The neural network models are subsequently used to perform sensitivity analysis. All electrical parameters are shown to be sensitive to conductor overlap. The inductance and capacitance of the pi equivalent circuit are sensitive to the bump height. However, the return loss (S₁₁) is insensitive to the change in bump height. The coplanar waveguide width has a significant impact on the s-parameters, as it affects the matching of flip-chip transitions     

Optical neural networks

Classical optical information processing and classical neural networks can be adapted and combined to create optical neural networks which offer significant and fundamental advantages over electronic neural networks in various well-defined cases. A systematic morphology of optical neural networks is presented. Special problems they create are discussed. The state of the art of their implementation is indicated, and some supportable speculations on their future are given     

Artificial neural networks

Examines the following questions associated with artificial neural networks: why people are interested in artificial neural networks; what artificial neural networks are, from the point of view of electronic circuits, and how they work; how they can be programmed and made to solve particular problems; and whether interesting problems can actually be put on such networks. The author then describes the current state of artificial neural network technology and the resulting challenges to people working on electronic devices     

高g冲击载荷下多层陶瓷电容结构失效分析

基于弹性力学和有限元方法对冲击载荷作用下多层陶瓷电容力学响应开展了理论和数值仿真计算。结果表明:由于自身结构特点,冲击载荷下电容易出现应力集中,基板变形对电容失效影响较大,分析了各工况下电容内部易失效位置及失效机理,其主要破坏特征为焊锡开裂造成脱焊。