Title :
High frequency and high resolution capacitance measuring circuit for process tomography
Author :
Yang, W.Q. ; Stott, A.L. ; Beck, M.S.
Author_Institution :
Dept. of Electr. Eng. & Electron., Univ. of Manchester Inst. of Sci. & Technol., UK
fDate :
6/1/1994 12:00:00 AM
Abstract :
A stray-immune AC capacitance measuring circuit has been developed for electrical capacitance tomography. For this application a high excitation frequency is essential to achieve high sensitivity and fast data collection rates, and also to reduce the effect of any conductive component in parallel with the measured capacitance. A high excitation frequency has been made possible by using some novel methods: (a) a high frequency digital signal generator; (b) parameter-optimised AC amplifiers and (c) a phase-sensitive demodulator utilising CMOS switches. With a 500 kHz excitation signal the circuit has good linearity and stability, and a resolution of 0.035 fF
Keywords :
capacitance measurement; demodulators; production testing; signal generators; 0.035 fF; 500 kHz; CMOS switches; HF digital signal generator; capacitance measuring circuit; electrical capacitance tomography; fast data collection rates; high excitation frequency; high resolution; high sensitivity; parameter-optimised AC amplifiers; phase-sensitive demodulator; process tomography; stray-immune AC capacitance measuring circuit;
Journal_Title :
Circuits, Devices and Systems, IEE Proceedings -
DOI :
10.1049/ip-cds:19941019
