在声系统分频器中电容器的比较

讨论了电容器影响音质的客观测量参数及听觉试验方法,对主观听音的评价结果进行了统计分析.特别讨论了K73-16电容器的表现.最后给出了电容器的主观音质评价与结论.希望对广大音箱设计者选用分频器电容有较大的参考作用.     

基于性能退化数据的金属化膜电容器可靠性评估

在对激光惯性约束聚变试验装置所用金属化膜脉冲电容器进行可靠性分析时,利用假设其寿命分布为Weibull分布的传统可靠性分析方法所得结果不能满足工程要求.作者通过分析电容的退化机理,给出了一个该型电容器的寿命分布模型,模型的求解是利用电容器的退化数据进行的,它具有比Weibull分布模型更为精确的特点,在工程实践中使用该模型对该型电容器进行可靠性分析可以大量的节约试验成本且结果精度更高.     

液晶盒的电容特性

液晶盒外加一定的电压,会改变液晶分子的取向排列,这样液晶层的有效介电常数也会随之发生改变。如果把液晶盒看作一个电容器,其电容也会有所改变。本论文理论研究强锚泊混合排列向列相液晶盒的电容特性,基于液晶弹性理论和变分原理,理论推导液晶盒系统的平衡态方程及电容的解析表达式,通过Matlab软件数值模拟了此液晶盒的电容-电压曲线和指向矢分布曲线,并对其电容特性进行了分析。     

测定固态试样相对电容率的几种方法

测定电介质材料的相对电容率,最好采用板状试样,因此以平行板电容器为载体测定固态试样的相对电容率是较优的方法.从可操作性及便捷性来看,测定试样相对电容率的方法有三种:一是以干燥空气环境代替真空环境,运用相对电容率的基本定义式进行测定;二是运用直流电路中已知电容器与待测电容器的串联关系,结合电容器电容的基本计算公式进行测定;三是综合运用交流电路中电容器电流有效值、电压有效值、容抗之间的关系式,及其电容、容抗的基本计算公式进行测定.     

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。     

双电层电容器及其应用

双电层电容器是具有电池和电容双重特性的新型电子元件,主要用于存储器备用电源、停机及关机备用电源、瞬间断电备用电源以及汽车能源再生系统。文中介绍了双电层电容器的设计原理以及它和电池及铝电解电容器的比较,并以哈尔滨大容电子有限公司生产的三种系列双电层电容器为例,对该产品及其应用作了介绍,最后给出了使用双电层电容器的注意事项。     

碳纳米管作为超大容量离子电容器电极的研究

本文采用碳纳米管作为超大容量离子电容器的电极材料,研究了硝酸改性处理、粘结剂对电极的电容器性能的影响,探讨了其电容的形成机理.当用硝酸改性处理的碳纳米管作电极,用30%(wt)的H₂SO₄作电解质溶液时,所得超大容量离子电容器不仅能形成双电层电容,也能形成赝电容,从而得到了69F/g的比电容;同时碳纳米管电极超大容量离子电容器具有良好的频率响应特性.     

可调真空电容拉杆的维护创新

可调真空电容器的拉杆在长时间使用后容易出现上下活动不灵活,甚至卡死.本文研究了可调真空电容器的结构原理,分析了可调真空电容器卡死的原因,有针对性地提出了对可调真空电容器拉杆进行清洁、润滑维护的方法,并设计了专用维护工具.该方法操作简单、节省时间,维护后可使可调真空电容保持转动灵活,甚至挽救卡死的真空电容,延长其使用寿命.     

一类零电流谐振开关电容变换器的特性分析

具有零电流开关特性的谐振开关电容变换器是开关电容变换器的一种新拓扑形式.本文着重分析电路寄生参数和变换器运行条件对该类谐振开关电容变换器稳态特性的影响,推出变换器输出电压和效率的数学表达式,为研究负载或输入电压变化时变换器的输出性能提供了分析和设计依据.基于输出电压表达式,还提出谐振开关电容变换器的频率控制方案.全文以一个降压式谐振开关电容变换器为例详细说明公式的推导过程,并将此稳态特性分析推广到其它类型的谐振开关电容变换器.最后,文中设计了一台12V/5V/2.5A降压式谐振开关电容变换器样机,实验结果验证了本文的理论分析结果.     

薄衬底共面波导的特性分析

本文推导出了薄衬底共面波导特性参数计算的近似解析表达式,避免了薄衬底保角变换中的"拥挤现象".利用该表达式并结合部分电容法可以计算在导体与衬底之间加薄绝缘层的共面波导的特性参数,分析结果与实验数据相符合.最后还对有薄绝缘层的硅衬底共面波导的损耗因子进行了分析.     

多导体电容系统多端口表示方法

部分电容是工程电磁场课程的一个重要内容，是电气领域经常应用的重要知识。结合微分形式电荷守恒方程和等效电路模型获得了无损耗多导体电容系统部分电荷守恒方程；基于正弦稳态电路结点导纳法得到了用部分电容和支路电压表示的多端口库伏关系；以3+1多导体电容系统为例，讨论了多导体电容系统的部分电容、感应系数矩阵和电位系数矩阵对应元素关系。该教学思路在教学应用中更易被学生理解和接受。     

Thermodynamic considerations of p-n junction capacitance

Recently, accurate solutions for the hole and electron densities and the electric field in a $\text{p-n}$ junction have become available. By use of these solutions it is possible to calculate $\text{p-n}$ junction capacitance more accurately. The literature contains several different viewpoints on the details of the calculation of junction capacitance. In this paper several formulations are briefly reviewed and a numerical comparison is given for an asymmetrical $\text{p-n}$ step junction. Space-charge capacitance and diffusion capacitance are shown to be well-defined quantities even if the depletion approximation is not valid. An extension of the so-called “energetic” definition of capacitance is presented. In particular, it is shown that the definition involving energy stored in the electrical field of a junction is valid only for large reverse bias. The range of validity may be extended to any bias, by consideration of both chemical and electrical energy: i.e., the total thermodynamic energy stored in the junction.     

Comb Capacitor Structures for On-Chip Physical Uncloneable Function

Planar inter-digitated comb capacitor structures are an excellent tool for on-chip capacitance measurement and evaluation of properties of coating layers with varying composition. These comb structures are easily fabricated in a single step in the last metallization layer of a standard IC process. Capacitive coupling of these structures with a coating layer is modelled based on the electric field distribution to have a detailed understanding of contributing capacitance components. The coating composition is optimized to provide maximum spread in capacitance values of comb capacitor structures. This spread in measured capacitance values can be used to implement a physical uncloneable function (PUF). A PUF is a random function which can be evaluated only with the help of a physical system. We present an on-chip capacitive PUF for chip security and data storage in which the unlock key algorithm is generated from capacitors which are physically linked to the chip in an inseparable way. The strength of this key increases with the spread in capacitance values and measurement accuracy.      

High-speed mid-IR modulator using Stark shift in step quantum wells

We show in calculations that there is a capability for high speeds with a low applied voltage in modulators based on intersubband transitions in step quantum wells (QWs). A waveguide based on surface plasmons is assumed to achieve the necessary tight confinement of the optical field. In a structure with 8 GaInAs-AlGaInAs-AlInAs step QWs, we obtain a device capacitance of 14 fF corresponding to a RC limitation of electrical f_{3 dB}=190 GHz. The extinction ratio of 6.6-μm light is 10 dB at an applied voltage of 0.9 V and T=300 K. By simple reasoning, we find that the device capacitance is approximately proportional to the absorption linewidth cubed when the linewidth is considered in the device design. Thus, the linewidth is very decisive for the modulation speed. We propose to place the dopants asymmetrically in the barriers in order to reduce broadening caused by doping induced potential fluctuations. In addition, the doping levels in the outermost barriers of the multi-QW structure are proposed to be reduced and asymmetrical, in order to achieve a uniform electric field over the step QWs, which is shown to increase the achievable f_{3 dB} very markedly     

“视景仿真”课程教学设计方案

本文提出"视景仿真"课程教学设计方案和教学创新思路。我们通过理论联系实际、结合实际研究课题、开拓学生在视景仿真领域学习的知识面,加深学生对视景仿真技术的理解,培养学生理解和运用视景仿真知识的能力。课程教学内容安排循序渐进、由浅入深,教学手段形象生动。教学实践表明,本课程的建设内容合理,在教学中取得了良好的教学效果。     

A reflection array of loaded microstrip radiators

A planar reflection array consisting of a primary radiator and an array of secondary microstrip radiators such that the phases of the fields generated by these radiators are identical in the direction of radiation is considered. This identity is attained by means of a forced phase step of the reradiated field. An approximate method for calculating the phase step of the reflected field relative to the phase of the incident field that arises during reradiation of the incident signal by an element of the reflection array is proposed. The method is based on the theory of dipoles and the reciprocity theorem. Dependences of the phase step on the dimensions of the antenna and the reactive stub, as well as the capacitance of the capacitor formed by the slot cut in the antenna, are studied. The calculation method is extended to the case of a two-stack microstrip antenna. A method is proposed for setting the maximum of the radiation pattern of this reflection array in a specified direction via the use of an electric signal to control the capacitances of the capacitors in the array elements.     

p-i-n InP/InGaAs光电探测器电流及电容特性研究

为了实现高灵敏度探测,红外探测器需要得到优化。利用Silvaco器件仿真工具研究了p-i-n型InP/In_0.53Ga_0.47As/In_0.53Ga_0.47As光电探测器结构,模拟了结构中吸收层浓度和台阶宽度对暗电流及结电容的影响。结果表明,随着吸收层掺杂浓度的逐渐增大,器件暗电流逐渐减小,结电容逐渐增大;当台阶宽度变窄时,器件暗电流随之减小,结电容也随之变小。最后研究了光强和频率对器件结电容的影响：在低光强下,器件结电容基本不变;当光强增大到1 W/cm²时,器件结电容迅速增大;器件结电容随频率的升高而减小,其峰值由缺陷能级引起。     

p-i-n InP/InGaAs光电探测器的电流及电容特性研究

为了实现高灵敏度探测,红外探测器需要得到优化。利用Silvaco器件仿真工具研究了p--i--n型InP/In0.53Ga0.47As/In0.53Ga0.47As光电探测器的结构,并模拟了该结构中吸收层浓度和台阶宽度对暗电流以及结电容的影响。结果表明,随着吸收层掺杂浓度的逐渐增大,器件的暗电流逐渐减小,结电容逐渐增大。当台阶宽度变窄时,器件的暗电流随之减小,结电容也随之变小。最后研究了光强和频率对器件结电容的影响。在低光强下,器件的结电容基本不变;当光强增大到1 W/cm2时,器件的结电容迅速增大。器件的结电容随频率的升高而减小,其峰值由缺陷能级引起。     

高速长波长谐振腔增强型光探测器的瞬态性能研究

基于谐振腔增强型(RCE)光探测器的实际设计和制作模型,提出了综合器件的隔离层及器件的串联电阻、结电容等参数的高速长波长RCE光探测器的瞬态响应特性的表达式,包括器件的冲击响应、阶跃响应和脉冲响应.从理论上详细地研究了高速长波长RCE光探测器的瞬态响应特性,最后给出了不同器件结构参数的计算结果.     

SOI铁电负电容晶体管亚阈值特性研究

随着微电子技术进入纳米领域,功耗成为制约技术发展的主要因素,因此,低功耗器件成为半导体器件领域的研究热点。负电容场效应晶体管基于铁电材料的负电容效应可有效地降低器件的亚阈值摆幅,从而降低器件的功耗。该文设计了一种基于绝缘体上硅(SOI)结构的铁电负电容场效应晶体管,利用TCAD Sentaurus仿真工具对负电容晶体管进行仿真研究,得到了亚阈值摆幅为30.931 mV/dec的负电容场效应晶体管的器件结构和参数。最后仿真研究了铁电层厚度、等效栅氧化层厚度对负电容场效应晶体管亚阈值特性的影响。