极微小电容的检测技术研究
发布时间：2018-07-16 09:17
【摘要】：电容测微技术具有低功耗、高精度、动态性能好、稳定性高和非接触测量等特点，，广泛应用于位移、液位、压力等参数的测量。随着超精密制造及现代工业生产的发展对检测精度要求越来越高，在微位移测量领域检测精度已达到纳米量级，纳米级位移变化对应的电容变化在fF量级，寄生电容干扰在pF量级，在如此大背景噪声下实现弱信号检测是提高电容测微精度亟需解决的基础性问题。 针对以上问题，本论文首先对四种电容测量方法原理及优缺点进行调研，最终选择了交流激励式作为本课题采用的电容测量方法。交流激励式电容测量系统主要包括前级电路、信号发生单元和信号解调单元，对各单元传统实现方式进行分析和优化，在此基础上完成系统设计。本论文完成的主要工作如下： 1、电容位移传感器电容测量电路指标分析及系统输入确定 对衡量电容测量系统性能的噪声、分辨率、带宽等指标从定义、原理及测量方法等方面进行阐述与分析。电容变化范围是设计电容测量系统的输入，采用电磁仿真软件CST建立了电容传感器模型，通过仿真确定了系统输入范围。 2、极微小电容测量系统设计 前级电路用以实现C-V(电容-电压)转换，其性能对系统分辨率起着决定性的作用。在前人研究基础上本文提出了一种新的电容桥电路，该电容桥包括测量臂和参考臂，测量臂测得的电容传感器电压通过1:1放大器引到参考臂，将参考臂输出电压乘以合适的倍数反馈到激励源，这样可以提高系统抗干扰能力并且增大前级电路输出电压变化范围。前人采用的桥式电路由两个激励源，一个参考电容和电容传感器组成，通过调节激励源电压使桥电路达到平衡此时电容传感器电容与参考电容比值等于两个激励源电压之比，通过比例关系可以得到电容传感器电容值。与桥式电路相比，电容桥电路具有结构简单、动态性好、抗干扰能力强和测量精度高等特点。 信号发生单元采用ADI公司高精度性能优良的DDS芯片实现。信号解调单元包括检波电路和低通滤波器，检波电路采用开关全波检波，低通滤波器采用FDNR滤波器。 在上述方案基础上完成极微小电容检测系统设计，并且搭建实验平台，对所设计系统进行相关实验测试，测试结果表明：该系统在150~650um量程范围内可以实现30nm分辨率，示值稳定性0.1mV/30min。
[Abstract]:Capacitive micrometer has the advantages of low power consumption, high precision, good dynamic performance, high stability and non-contact measurement. It is widely used in the measurement of displacement, liquid level, pressure and other parameters. With the development of ultra-precision manufacturing and modern industrial production, the precision of measurement has reached the nanometer order, and the capacitance corresponding to the change of nanometer displacement is in the order of FF. The parasitic capacitance interference is in the order of PF and the weak signal detection under such a large background noise is a basic problem that needs to be solved to improve the accuracy of capacitance measurement. Aiming at the above problems, this paper firstly investigates the principle, advantages and disadvantages of four capacitance measurement methods, and finally chooses AC excitation as the capacitance measurement method adopted in this subject. The AC excitation capacitance measurement system mainly includes the front-stage circuit, the signal generating unit and the signal demodulation unit. The traditional realization of each unit is analyzed and optimized, and the system design is completed on the basis of the analysis and optimization. The main work of this paper is as follows: 1. The analysis of capacitive displacement sensor capacitance measurement circuit index and the determination of system input to measure the capacitance measurement system performance of noise, resolution, bandwidth and other indicators from the definition, The principle and measurement method are expounded and analyzed. The range of capacitance variation is the input of designing capacitance measurement system. The capacitance sensor model is established by using the electromagnetic simulation software CST. The input range of the system is determined by simulation. 2. A very small capacitance measuring system is designed to realize C-V (capacitance-voltage) conversion. Its performance plays a decisive role in the resolution of the system. On the basis of previous studies, a new capacitance bridge circuit is proposed in this paper. The capacitance bridge consists of a measuring arm and a reference arm. The voltage of the capacitance sensor measured by the measuring arm is led to the reference arm by the 1:1 amplifier. The output voltage of the reference arm is multiplied by the appropriate multiple to the excitation source, which can improve the anti-interference ability of the system and increase the range of the output voltage of the former circuit. The bridge circuit is composed of two excitation sources, a reference capacitance and a capacitive sensor. By adjusting the voltage of the excitation source, the bridge circuit is balanced when the ratio of capacitance to reference capacitance of the capacitive sensor is equal to the ratio of the voltage of the two excitation sources. The capacitance value of capacitive sensor can be obtained by proportional relationship. Compared with the bridge circuit, the capacitor bridge circuit has the advantages of simple structure, good dynamic, strong anti-interference ability and high measurement precision. The signal generating unit is implemented by ADI DDS chip with high precision and excellent performance. The signal demodulation unit consists of demodulation circuit and low-pass filter. The detection circuit uses full wave detector on switch and FDNR filter is used for low-pass filter. On the basis of the above scheme, the design of the very small capacitance detection system is completed, and the experimental platform is built. The test results show that the system can realize the 30nm resolution in the range of 150~650um range. The stability is 0.1 MV / 30 min.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM934.23;TP212
[Abstract]:Capacitive micrometer has the advantages of low power consumption, high precision, good dynamic performance, high stability and non-contact measurement. It is widely used in the measurement of displacement, liquid level, pressure and other parameters. With the development of ultra-precision manufacturing and modern industrial production, the precision of measurement has reached the nanometer order, and the capacitance corresponding to the change of nanometer displacement is in the order of FF. The parasitic capacitance interference is in the order of PF and the weak signal detection under such a large background noise is a basic problem that needs to be solved to improve the accuracy of capacitance measurement. Aiming at the above problems, this paper firstly investigates the principle, advantages and disadvantages of four capacitance measurement methods, and finally chooses AC excitation as the capacitance measurement method adopted in this subject. The AC excitation capacitance measurement system mainly includes the front-stage circuit, the signal generating unit and the signal demodulation unit. The traditional realization of each unit is analyzed and optimized, and the system design is completed on the basis of the analysis and optimization. The main work of this paper is as follows: 1. The analysis of capacitive displacement sensor capacitance measurement circuit index and the determination of system input to measure the capacitance measurement system performance of noise, resolution, bandwidth and other indicators from the definition, The principle and measurement method are expounded and analyzed. The range of capacitance variation is the input of designing capacitance measurement system. The capacitance sensor model is established by using the electromagnetic simulation software CST. The input range of the system is determined by simulation. 2. A very small capacitance measuring system is designed to realize C-V (capacitance-voltage) conversion. Its performance plays a decisive role in the resolution of the system. On the basis of previous studies, a new capacitance bridge circuit is proposed in this paper. The capacitance bridge consists of a measuring arm and a reference arm. The voltage of the capacitance sensor measured by the measuring arm is led to the reference arm by the 1:1 amplifier. The output voltage of the reference arm is multiplied by the appropriate multiple to the excitation source, which can improve the anti-interference ability of the system and increase the range of the output voltage of the former circuit. The bridge circuit is composed of two excitation sources, a reference capacitance and a capacitive sensor. By adjusting the voltage of the excitation source, the bridge circuit is balanced when the ratio of capacitance to reference capacitance of the capacitive sensor is equal to the ratio of the voltage of the two excitation sources. The capacitance value of capacitive sensor can be obtained by proportional relationship. Compared with the bridge circuit, the capacitor bridge circuit has the advantages of simple structure, good dynamic, strong anti-interference ability and high measurement precision. The signal generating unit is implemented by ADI DDS chip with high precision and excellent performance. The signal demodulation unit consists of demodulation circuit and low-pass filter. The detection circuit uses full wave detector on switch and FDNR filter is used for low-pass filter. On the basis of the above scheme, the design of the very small capacitance detection system is completed, and the experimental platform is built. The test results show that the system can realize the 30nm resolution in the range of 150~650um range. The stability is 0.1 MV / 30 min.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM934.23;TP212
【参考文献】
相关期刊论文 前9条
1 张涛;陈亮;;现代DDS的研究进展与概述[J];电子科技;2008年03期
2 范结义;高成;;商用电磁仿真软件的现状与发展[J];电子科技;2011年01期
3 郭抗;巩岩;;6-PSS型光学元件精密轴向调节机构[J];光学精密工程;2013年10期
4 冯佳;李佩s
本文编号：2125932
本文链接：https://www.wllwen.com/kejilunwen/dianlilw/2125932.html
