电容传感器微弱电容测量电路的仿真研究

本文研究了电容传感器的三种微弱电容测量电路,分析和比较了它们的优缺点.基于对抗高过载低量程电容加速度传感器的设计要求,选择了一种基于电荷放大原理的电容测量电路方案,进行重点研究.并对该电路需要的元器件进行仔细的考虑和选择.运用Altera公司的软件MaxplusⅡ的VHDL语言,通过对复杂可编程逻辑器件CPLD进行编程,以产生开关控制时序,从而很好地实现了该测量电路的功能.     

开关电容法电容测量电路

本文介绍一种闭环开关电容法电容测量电路的基本原理，数学模型及其稳定条件，其结构简单，性能优越，可在各种电容传感器测量电路中的使用。     

重新评价基于充放电原理的微电容测量电路

基于充放电原理的电容测量电路是目前微电容测量中广泛采用的一种测量电路，其最大的特点是电路具有抗分布电容特性且简单实用。本文对基于充放电原理的微电容测量电路进行了深入研究，利用微分方程的数值解法，通过计算机仿真得到了各种参数对电路的影响。     

用于气固两相流在线测量的ECT电容测量电路

电容层析成像(ECT)技术是目前最具发展前景的多相流参数检测方法.介绍了12电极ECT成像系统的测量原理及设计方法.研制了一种交流激励的微电容测量电路,该电路具有较强的抗杂散电容性能、结构简单、容易实现等优点,较好地解决了电子开关的电荷注入效应对测量分辨力的影响问题.经试验证明可达到的实际分辨力为0.04fF.     

开关电容滤波器的原理及应用设计

本文首先分析了开关电容取代电阻的原理以及由有源RC滤波器向开关电容滤波器(SCF)转换的原理;运用状态变量法电路对MF10通用二单元开关电容滤波器进行了应用设计,最后指出了开关电容滤波器共有的一些特征及应注意的问题。     

基于开关电容电路的模拟滤波器的设计

文章介绍了开关电容电路的基本结构和工作特性．并通过实例阐述了利用开关电容电路技术可以实现小型化高精度、高稳定性的音频模拟滤波器。     

基于V/T变换的电容传感器新型电容测量电路

提出了一种基于V／T变换的用于电容传感器的电容测量电路。它将被测微小电容变化量转换成时间信号并由单片机进行处理，电路结构简单，电路中没有影响测量稳定性和产生零点漂移的元器件，大幅度地降低了测量过程中的噪声。     

高精度微小电容测量电路的研制

介绍了一种数字电路与模拟电路相结合的测量电路，可用于微小电容的测量。实验结果表明，电路的线性度、分辨率和稳定性等性能指标均达到了测量要求。     

MEMS电容传感器小电容的测量

本文首先介绍了一种MEMS电容式微硅加速度计的结构和等效电路,阐述了开关电容放大器的工作原理和输出电压与电容的关系,重点讨论了用开关电容技术测量微硅加速度计小电容的方法.     

非理想效应对开关电容电路的影响

组成开关电容电路的主要元器件的实际特性都是非理想的,这些非理想特性影响到开关电容电路的精度、稳定度和电路的工作频率等.文章就运算放大器的非理想特性对开关电容电路性能的影响进行了较详细地分析研究,并提出其改进方法.     

电容层析成像系统中电容传感器参数优化设计

电容层析成像系统中,图像重建的质量主要依赖于电容敏感场分布的均匀性,这一性质又由传感器的几何和材料参数决定,因此传感器的设计尤为重要．根据敏感场颁上的均匀性,灵敏程度和电容测量技术,确定了传感器的优化参数;在多因素轮换的基础上,采用正交设计法进行电容传感器参数的计算机辅助设计,从而快速地获得一组最优参数．在实际应用中,概据此优化参数制造的电容传感器获得了较为理想的重建图像．     

Capacitance pressure pickups

The results of experimental investigations of miniature capacitance pressure pickups are reported. Translated from Izmeritel'naya Tekhnika, No. 5, pp. 35–37, May, 1996.     

Capacitance of silicon pixels

Capacitance measurements have been made on silicon pixel sensors of types n⁺ on n, p⁺on n, and n⁺ on p. The arrays test a variety of implant and gap widths, and the n⁺ on n devices test several p-stop designs. The measurements examine inter-pixel and backplane contributions and include studies of temperature dependence. Measurements were made before and after irradiation with fluences relevant to LHC experiments and Fermilab Tevatron Run 2.     

Electrical Capacitance Volume Tomography

A dynamic volume imaging based on the principle of electrical capacitance tomography (ECT), namely, electrical capacitance volume tomography (ECVT), has been developed in this study. The technique generates, from the measured capacitance, a whole volumetric image of the region enclosed by the geometrically three-dimensional capacitance sensor. This development enables a real-time, 3-D imaging of a moving object or a real-time volume imaging (4-D) to be realized. Moreover, it allows total interrogation of the whole volume within the domain (vessel or conduit) of an arbitrary shape or geometry. The development of the ECVT imaging technique primarily encloses the 3-D capacitance sensor design and the volume image reconstruction technique. The electrical field variation in three-dimensional space forms a basis for volume imaging through different shapes and configurations of ECT sensor electrodes. The image reconstruction scheme is established by implementing the neural-network multicriterion optimization image reconstruction (NN-MOIRT), developed earlier by the authors for the 2-D ECT. The image reconstruction technique is modified by introducing into the algorithm a 3-D sensitivity matrix to replace the 2-D sensitivity matrix in conventional 2-D ECT, and providing additional network constraints including 3-to-2-D image matching function. The additional constraints further enhance the accuracy of the image reconstruction algorithm. The technique has been successfully verified over actual objects in the experimental conditions     

A Principle for Capacitance Measurement, Suitable for Linear Evaluation of Capacitance Transducers

A principle for measurement of capacitance is shown, together with a practical realization. The inherent linearity of output voltage as function of capacitance makes the principle advantageous for the evaluation of capacitance transducers.     

数字化电容层析成像系统

基于电容敏感原理设计的数字化电容层析成像（ECT）系统,利用有限元法,分析了阵列电极结构对敏感场分布的影响,通过优化设计和仿真试验,改善了敏感场分布的均匀性;构建了以数字信号处理器（DSP）为核心、现场可编程门阵列（眦）协同工作的12电极的数字化ECT系统,提出了由离线预迭代和在线一步成像所构成的新的图像重建算法——预迭代法,其成像速度及精度均明显得到提高。     

A Switched-Capacitor Digital Capacitance Bridge

A switched-capacitor bridge has been developed for capacitance measurements. It consists of four arms connected between the low-impedance output and virtual ground nodes of an op-amp, and hence is insensitive to parasitic capacitances. The capacitance to be measured is first given a proportional charge. This charge is then compared successively with charges quantized by means of a programmable binary-weighted capacitor array, until a balance is reached. This digital balance operation makes it possible to accomodate an automatic calibration scheme, which affords, in conjunction with the parasitic-insensitive configuration, an accurate measurement. Error analysis has shown that a 10-bit quantization accuracy and a relative error as small as 0.1 percent are attainable when the bridge is fabricated in LSI circuit form using present MOS technologies. A prototype bridge built using discrete components has confirmed the principles of operation. Examples of measurement are also given.     

Thin-Film Capacitance Pressure Pulsation Sensors

The salient features of capacitance pressure pulsation sensors are presented.