时滞位置反馈对一类静电微传感器的吸合不稳定的控制研究

针对微结构在静电力作用下的吸合不稳定问题,考虑一类典型的单自由度静电驱动微传感器振动系统,将时滞位置反馈施加在系统的直流偏置电压上,研究引起微结构的动态吸合和吸合不稳定的系统参数条件,以及时滞反馈对吸合不稳定的抑制机理。运用Melnikov函数法得到时滞受控系统中引起结构吸合不稳定的交流电压的临界幅值。并基于时滞受控系统的安全域随控制参数的演变,定量上研究时滞反馈对吸合不稳定的控制。数值结果和理论分析均表明：在正的反馈增益系数和较小的时滞量下,时滞位置反馈能够有效地抑制静电驱动微结构的吸合不稳定现象。     

一类静电驱动双边电容型微谐振器振动系统的复杂动力学特性研究

以一类静电驱动双侧平行板电容型微谐振器为研究对象,基于分岔理论研究微结构的复杂动力学行为的机制。通过分析微结构动力系统的静态分岔,发现直流偏置电压的增大会直接引起微结构的静态吸合。在此基础上获得系统的多稳态解的解析形式,解析预测与数值结果吻合,研究发现系统的振动跳跃来源于双平衡点失稳引起的多稳态现象。进而发现继续驱动交流电压幅值的增大则会引起微结构的混沌和吸合不稳定现象。该结果对静电驱动微谐振器的设计中如何避免出现复杂响应具有实际意义。     

直梁结构光栅光调制器的机电特性分析与实验

介绍了直梁光栅光调制器的结构和原理,建立了器件的机电模型．利用能量法和卡式第二定理分析并得到器件的弹性系数;通过静电力与机械回复力的平衡,得到器件的驱动电压．结合器件的实际参数值,计算得到器件的工作电压为10．71V,吸合电压为11．46V．实验测得器件的实际工作电压为10．5V,吸合电压为12．2V,实验结果与理论分析基本一致．在1kHz脉冲电压的驱动下,器件响应的上升时间和下降时间分别为46．59μs和44．77μs;器件的响应频率约为5kHz．结果表明,加工的直梁光栅光调制器具有较低的驱动电压和较高的响应频率,能够满足微投影显示的要求．     

一种高性能横向接触式微机械RF开关的分析与设计

设计了一种新型横向接触式微机械RF开关，描述了其结构和工作原理．采用以电镀为主的工艺流程，并利用SU8光刻胶实现特殊器件结构，可实现Post-CMOS集成．利用模拟软件CoventorWare 2004和MEMS Pro 5．0（包含ANSYS8．0）协同设计，对该器件进行了静态、模态和瞬态分析，得到吸合电压和吸合时间等重要性能参数．尤其在瞬态分析时运用了集总参数建模的方法，简化了计算．该器件的吸合电压低于30V，在驱动电压为50V的情况下，吸合时间达到16．1ms．     

静电力平衡式MEMS电容薄膜真空计检测电路研究

静电力平衡式MEMS电容薄膜真空计量程宽、稳定性高,具有广阔的应用前景。测量电路是保证静电力平衡式MEMS电容薄膜真空计性能的关键因素。采用交流激励式检测方法,设计了一种微小电容检测电路,并利用软件仿真和实验测试进行验证。结果表明,该电路能够快速检测微小电容并将其转换为直流电压信号,分辨率为0.33 V/pF。此外,抗驱动电压干扰测试表明,该电路能够在1～100 V范围的直流驱动电压下正常工作,电容测量的输出电压最大标准差为0.010 249 V,并且具有优异的稳定性。     

直流小电压信号的远距离测量

在生产过程中，经常会遇到直流小电压信号的远距离测量，在这种情况下，二次仪表能否真正反映一次仪表信号?     

一类双边电容型微谐振器吸合不稳定及其时滞速度反馈控制

以一类典型的静电驱动双边电容型微谐振器为研究对象,基于全局分岔理论,研究微结构吸合不稳定的机理;在此基础上,在系统直流偏置电压上引入线性时滞速度反馈,对系统复杂动力学行为实施控制。通过引入独立参数,得出系统异宿轨道的精确解析表达,进而利用Melnikov方法预测微结构的异宿分岔条件,从而获得引起微结构吸合不稳定的交流电压阈值。数值算例与理论解析结果的吻合验证了时滞速度反馈控制能有效抑制该类双边电容型微结构吸合不稳定以及混沌等复杂动力学行为,该研究在优化控制微谐振器性能方面具有潜在的应用价值。     

一种WXGA液晶显示器的非晶硅栅极驱动电路

介绍了一种采用非晶硅薄膜晶体管制作的14.1英寸WXGA(1280×RGB×800)液晶显示器栅极驱动电路.该栅极驱动电路的主要特点是电路中所有的薄膜晶体管器件均不会长期工作在直流偏置电压下.这种电路结构设计能够极大地减小非晶硅薄膜晶体管的阈值电压漂移,从而保证该栅极驱动电路能够长期可靠地工作.实验结果表明:非晶硅薄膜...     

浅谈直流高压检定系统及其测量工作中的特殊问题

在电学的计量领域,要对高压信号进行测量,就要有一套完善的系统和装置,同时在高电压测量时很多情况下对于测量用仪器的结构、连线需要特别谨慎。文章简要分析了直流高压检定系统工作原理及组成,总结了在高电压测量过程中可能出现的特殊问题及避免措施。     

静电梳驱动RF MEMS滤波器动力学分析

静电梳驱动硅微机械滤波器在RF通信领域有重要应用。从振动力学的角度,对硅微机械滤波器的力电耦合动态特性进行分析。分析结果表明:硅微机械滤波器输出电压V_o(t)与梳状振子振动速度成正比。谐振状态下,静电力包含直流分量和倍频分量。直流偏置电压V_p可消除系统倍频振动,为后续检测电路设计提供便利。     

Digital Instrumentation for the Time Integral of the Square of a Slowly Fluctuating Voltage

A portable digital instrument is described that provides a decimal readout of 1) the time integral of the square of a fluctuating voltage and of the measuring time on two decimal displays, and 2) the amplitude distribution of the voltage. The instrument has no low-frequency limitations. For periodic inputs, measurement may take place over one cycle. For either periodic or random inputs, measurement may be made to commence on a start signal and run for a programmed time. Readout is available immediately at the end of the measuring time, so that the instrument can be used in on-line real-time process control. The voltage under measurement is sampled systematically, and the sampled data are processed using a unique special-purpose digital computer. The paper describes the principles on which measurements are based, and the design and error characteristics of an instrument in which, for most waveforms (e. g., sine, ramp, white noise), the maximum error is in the region of 1 percent and the upper frequency limit is about 1 kHz.     

载体加速度对静电驱动微机械陀螺响应的影响分析

载体的运动会导致微机械陀螺的响应发生变化,因而引起测量误差,甚至导致系统故障。针对载体运动对微机械陀螺响应的影响开展研究。考虑载体运动以及微陀螺的非线性支承刚度和非线性静电力,基于拉格朗日方程建立了系统的动力学方程。利用谐波平衡法结合留数定理求解了含分式非线性项的系统的周期响应,研究了载体加速度对系统响应特性的影响,发现驱动方向的载体加速度主要导致系统的灵敏度降低。检测方向的载体加速度除使得系统灵敏度降低,还会导致零偏,且零偏和加速度的大小成正比,但比例系数与驱动电压无关。驱动电压较小时,载体在检测方向较小的加速度对灵敏度和非线性度影响很小;而在驱动电压或者检测方向加速度较大时,系统的灵敏度急剧下降,且非线性度也发生了剧烈变化。     

基于约瑟夫森量子电压的谐波电压测量方法研究

约瑟夫森量子电压目前大多应用于正弦信号的测量,极少有针对谐波信号的研究。对可编程约瑟夫森电压基准应用于谐波检测的可行性进行了研究,实现谐波电压向量子电压过渡。在使用阶梯波交流量子电压进行谐波电压测量时,由于过渡过程和吉布斯现象的存在,部分数据出现较大波动;若将该部分处于过渡过程的数据纳入傅里叶变换,会导致恢复得到的信号幅值和相位失真。针对这一问题,提出了一种新的谐波电压计算方法:加权傅里叶变换。该方法通过将处于过渡过程的数据权重置零的方式,实现了谐波电压的准确测量。实验结果表明,谐波电压幅值和相位测量结果较理想,幅值测量标准差均小于1 μV,相位测量标准差均小于15 μrad。     

偏压对活性屏离子渗氮工艺的影响

通过对40C钢进行活性屏离子渗氮处理,研究了在活性屏离子渗氮工艺过程中工件所加的偏压对渗氮层的影响.试验结果表明,在不加偏压或偏压较低的情况下,对距离活性屏较近的工件,其表面有一定厚度的渗氮层形成,硬度提高;而距离活性屏较远的工件,其表面几乎没有渗氮层的形成,但当增大偏压至400～450 V时,工件表面产生弱的辉光放电...     

A Simple Method for the Calibration of Traditional and Electronic Measurement Current and Voltage Transformers

The calibration of measurement transformers represents a classical task in the practice of electrical measurements. Most commercial instruments that are expressly designed for this purpose found their working principle on a scheme that is based on the idea of Kusters and Moore. Although they can assure very high accuracy, the need to employ a high-performance electromagnetic circuit makes them very expensive and usually not suitable for measurements at frequencies that are higher than 50 or 60 Hz. For this reason, these kinds of instruments cannot be employed for the calibration of the new generation of current and voltage transducers, such as electronic measurement transformers, whose employment is growing in all the applications where wide bandwidth is required. In this paper, a new method for the calibration of electromagnetic voltage and current measurement transformers (VTs and CTs) and electronic voltage and current measurement transformers (EVTs and ECTs) is discussed, and a deep metrological characterization is carried out. The novelty of the proposed method is represented by a completely different approach to the measurement of the ratio and phase errors of the measurement transformers. The method is based on the proper digital signal processing of the signals that are collected at the secondaries of the transformer under test and of a reference transformer when the same signal is applied to their primary. Since no auxiliary electromagnetic circuits are required, this solution can be easily implemented in a simple and cost-effective way. In spite of its simplicity, the tests that are developed on a prototype clearly point out that the proposed system is suitable for the calibration of measurement transformers with precision class up to 0.1 in the frequency range from 50 Hz to 1 kHz.     

飞机电网直流电压畸变信号测试方法

随着飞机上非线性负载的增加,它们对电网的影响越来越引起人们的重视。本文采用模拟滤波和数字信号处理技术,完成了对飞机电气系统直流电压畸变的测试,给出了对某型飞机电网的实际测试结果。     

Nonlinear effects in varactor-tuned resonators

This paper describes the effects of RF power level on the performance of varactor-tuned resonator circuits. A variety of topologies are considered, including series and parallel resonators operating in both unbalanced and balanced modes. As these resonators were designed to produce oscillators with minimum phase noise, the initial small signal insertion loss was set to 6 dB and, hence, QL/Q0 = 1/2. To enable accurate analysis and simulation, S parameter and PSPICE models for the varactors were optimized and developed. It is shown that these resonators start to demonstrate nonlinear operation at very low power levels demonstrating saturation and lowering of the resonant frequency. On occasion squegging is observed for modified bias conditions. The nonlinear effects are dependent on the unloaded Q (Q0), the ratio of loaded to unloaded Q (QL/Q0), the bias voltage, and circuit configurations with typical nonlinear effects occurring at -8 dBm in a circuit with a loaded Q of 63 and a varactor bias voltage of 3 V. Analysis, simulation, and measurements that show close correlation are presented.     

低偏压下化学气相沉积金刚石薄膜的生长形貌研究

在微波等离子体化学气相沉积装置中，研究了偏压电压、甲烷浓度及沉积气压对金刚石晶形显露的影响。实验结果表明，生长时施加低的衬底偏压对金刚石的晶形显露有较大的影响，正的偏压有利于(111)面显露，负偏压有利于(100)面显露。在低偏压条件下生长时，低的沉积气压和甲烷浓度有利于(111)面显露；而高的气压和甲烷浓度有利于(100)面显露。过高的甲烷浓度将恶化金刚石质量，出现菜花状组织，无明显的晶面显露。     

直流负偏压对类金刚石薄膜结构和性能的影响

利用直流-射频-等离子体增强化学气相沉积技术在单晶硅表面制备了类金刚石薄膜，采用原子力显微镜、Raman光谱、X射线光电子能谱、红外光谱、表面轮廓仪和纳米压痕仪考察了直流负偏压对类金刚石薄膜表面形貌、微观结构、沉积速率和硬度等性能的影响。结果表明：无直流负偏压条件下，薄膜呈现有机类聚合结构，具有较低的SP3含量和硬度；叠加上直流负偏压后，薄膜具有典型的类金刚石结构特征，SP3含量和硬度得到了显著的提高；但随着直流负偏压的升高，薄膜的沉积速率和H含量逐渐降低，而SP3含量和硬度在直流负偏压为200V时出现最大值，此后逐渐降低。     

Hole trapping in polydiacetylene field effect transistor studied by optical second harmonic generation

Hole trapping in polydiacetylene field effect transistor (PDA-FET) was studied by the electric field induced second harmonic generation (EFISHG). Response of SHG signal from PDA-FET with an application of external voltage was monitored. Applying positive voltage to source and drain electrodes with respect to gate electrode, SHG signal was not observed during bias application, whereas the signal was enhanced after turning off the bias. Since positive bias promotes hole injection from source and drain electrodes, electric field formed by trapped holes in PDA layer activated the SHG signal. Microscopic SHG measurement implies that the trapped holes are concentrated around source and drain electrodes.