摘要
本文针对介电常数和位移信息等应用领域对微电容测量的精度和功能要求,采用一种基于充放电原理的具有高抗寄生效应的微电容测量电路,由C8051F345实现数字化和多种软件功能。其中,利用片内可编程计数器阵列实现电子开关的死区控制,消除电路开关交叠期及电荷泄露,提高了测量精度。同时,片内10位A/D对模拟放大电路部分的输出电压完成模拟/数字转换,进而由软件实现滤波等功能。该数字式微电容测量系统包括电容测量模块、介电常数测量模块以及位移测量模块,具备测量模式选择、量程自动调节、数据实时或定时储存等功能,测量结果由液晶显示,由串口、USB接口和网口实现与上位机及网络的通信。
To satisfy the high precise requirement of micro-capacitance measuring in dielectric constant and displacement application occasions, we present an applicable micro-capacitance measuring circuit system that is immune from stray capacitance based on the charging/discharging principle. C8051F345 is used to realize digitization and several software functions. The Programmable Counter Array on this chip eliminates intersection between the electronic switches and decreases the electric leak through controlling the dead zone time of the electronic switches, thus ensuring the measuring precision. Meanwhile, the output voltage of analog circuit is digitized by on-chip tens place A/D and filtered by the software. This system includes three blocks： capacitance measuring block, dielectric constant measuring block and displacement measuring block. It also has several functions such as selection of measuring mode, automatic regulation of span, and true time and definite time storage of data, etc. The results of the measurement can be displayed on a liquid crystal screen, and the communication with the computer and internet is realize by serial-port, USB interface, and terminal port.
出处
《电子测量技术》
2007年第10期127-130,共4页
Electronic Measurement Technology
关键词
微电容
充放电原理
C8051F345
死区
micro-capacitance
charging/discharging principle
C8051F345
dead zone
