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。     

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。     

MEMS电容薄膜真空计微电容测量研究进展

MEMS电容薄膜真空计的小型化和整体性能与微电容测量电路密切相关。由于不同领域的应用需求,MEMS电容薄膜真空规管具有不同的敏感电容结构,而相应的微电容测量法也不同。单侧电极微电容测量法电路结构简单,易于实现;双侧电极微电容测量法电路结构较复杂,但该电路可以减小寄生电容及温度的影响而获得高分辨率;静电力平衡式结构下微电容测量法用闭环电路,在高精度测量的同时还能拓宽真空计的动态范围。介绍了测量原理、电路结构及性能,可以看出,具有精度高、功耗低、易集成的特点,能够应用于多种不同类型的MEMS电容式传感器的微小电容测量电路,对今后MEMS应用从航空航天等高精尖领域向人工智能物联网领域的拓展具有重要意义。     

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。     

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。     

电容传感器微弱电容测量电路中CPLD的应用

本文针对微弱电容测量的传统方法——充放电法和交流法的缺点．选用了一种基于电荷放大原理的电容测量电路原理，该电路通过设计合理的开关时序．有效的消除了电子开关的电荷注入效应。这里．该电路的开关时序用MAX7000S系列的复杂可编程逻辑器件CPLD编程实现。通过实验发现，该电路达到了较高的分辨率。     

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.     

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。     

电容成像技术及其应用

过程成像技术是近十多年来发展起来的一种新型过程检测技术，可以广泛应用于石油、化工、电力及冶金等行业中的两相流测量。本文结合清华大学自动化系过程成像小组研制的电容成像系统，介绍了电容成像技术的发展和现状，包括电容成像基本原理、微电容测量电路和图像重建算法等。论文给出了现有系统在小型流化床模拟装置上进行测量和连续图像重建的实验结果，并进行了分析。此外，论义对电容成像技术今后的发展作出了展望。     

薄膜电容真空计电源的研究

介绍了利用交流电桥和相敏检波（PSD）原理设计的薄膜电容真空计电源的电路实施方案、主机电路结构和实测性能，对其中关键的小电容测量方法进行了深入的研究，在8h内测量，电容差值的漂移可小至10－3pF。主机结构采用微机控制和真空计模块化设计，可构成复合真空计或用于组装其他真空计。初步测试结果表明，这种真空计用单规管可以实现从大气至1Pa，覆盖五个数量级的真空度测量。     

A microprocessor-based switched-battery capacitance meter

A microprocessor-based, switched-battery capacitance meter has been developed. It consists of an analog part, based on a previously designed capacitance meter, and a digital part in which a microprocessor and a timer perform the main functions. The capacitance is measured indirectly by means of a time constant measurement. Two phases of the measurement process are involved in measuring the capacitance. The first phase, when a capacitor is charged, is based on the software counter-timer measurements. The second phase, when the capacitor is discharged, requires a hardware timer controlled by the microprocessor. The digital hardware reflects a different approach than used for the previous construction     

Measuring the capacitance of capacitors with large losses

Conclusions The application range of the beating method and similar methods for measuring capacitances with large losses are limited by errors which are inherent in these methods and are due to the loss resistances affecting the measurement results (12).The effect of losses on the capacitance measurements is completely eliminated in measuring circuits with modulated parameters. The utilization of circuits with an external modulation serves to raise the sensitivity of capacitance measurements. The automation of these circuits makes them very promising for designing commercial instruments.Translated from Izmeritel'naya Tekhnika, No. 8, pp. 58–61, August, 1968.     

A self-balancing circuit to measure capacitance and lossconductance for industrial transducer applications

This paper describes a capacitance and loss conductance measuring circuit for the use in industrial transducers. The circuit is based on self-balancing principle and it is immune to stray capacitance. The balancing process is controlled by a micro-controller. The capacitance and loss conductance are represented by the digital feedback signals or by the combination of the feedback signals with the forward path signals. Experimental results show that the circuit has high resolution (0:04 fF) and good linearity (0.999)     

A high frequency stray-immune capacitance transducer based on thecharge transfer principle

A stray-immune capacitance measuring instrument based on the charge transfer principle is described. It has a programmable measurement frequency up to several megahertz and is inexpensive and suitable for integration onto a single chip. The effects of stray capacitances, including those of the switching components, have been eliminated by using a special switching arrangement, resulting in a baseline drift of 0.02 pF (at 1-MHz measurement frequency) over a 12-h period     

Manual / automated capacitance box using micro-controller technique

A capacitance box contains more than one decade capacitance. These decades have different capacitance ranges to get a much wider range of the capacitance steps obtained by the whole box. In general, a decade capacitance is constructed by ten capacitors to give ten manual capacitance steps. In this paper, a new design of a capacitance box is presented using two-decade capacitances. Each one of them is constructed by four capacitors only. This capacitance box is automatically controlled by especially designed programs using the Lab VIEW to provide a combination of 100 sequential capacitance steps from the common output of the two decades. These capacitance values can be used for the automatic calibrations of the capacitance measurement devices. Also, its capacitance steps can be obtained by manual way according to the user requirements, through an assembly language program using push-button switches. Control of each decade in this box depends on a micro-controller technique and four electronic relays as clearly investigated in this paper. Practical design, fabrication, and calibration for one decade of the capacitance box have been demonstrated in details through this research. The second decade in this box is the same as the first one, but it has different value of the capacitance per step.     

1.4 Fast volume determination using a differential capacitance manometer

The reliable pressure readings with a capacitance manometer are the basis for a new type of instrument designed for accurate and rapid measurements of capillary volumes. The basic measuring principle is based on expansion of air atmospheric pressure enclosed in a known volume into a pre-evacuated cylinder so that the enclosed volume will cause a reduced pressure in the cyllinder. The same is done with the air in an unknown volume into another identical pre-evacuated cylinder. A differential capacitance manometer is then used to measure the difference in pressure between the two cylinders with a high degree of accuracy. This difference in pressure is shown to be ainear function of the difference in volume between the unknown and the known volume. The accuracy and repeatability of the instrument is better than 0.5%.     

电容/电压转换电路CAV424及其在油品含水率测量的应用

提出了一种电容传感器调理电路的新方法,引入了用于电容/电压信号转换的集成电路CAV424,以及CAV424在油品含水率测量中的应用。     

Bridge converters of resistance,capacitance and inductance into frequency

Summary As a result of the above work we have established a range of frequency-sensitive bridge circuits which can be balanced by adjusting only the frequency of the supply voltage and can serve as high-precision converters of resistance, capacitance or inductance into frequency. These converters possess a number of valuable properties which make them very convenient for working in centralized control and remote measuring systems.     

A method and instrument for measuring the capacitance switching time of nonlinear capacitors

A device and procedure for measuring the switching time of the capacitance of nonlinear microwave capacitors, based on ferroelectric films and bulk ceramics (variconds) when acted upon by controlling electric field pulses, are considered. The method can be used to measure high-speed semiconductor varactors, microelectromechanical components and the residual polarization of capacitors based on a linear ceramic.