Measurement of small capacitance variations

Author

Marioli, D. ; Sardini, E. ; Taroni, A.

Author_Institution

Dipartimento Autom. Ind., Brescia Univ., Italy

fYear

1990

fDate

11-14 June 1990

Firstpage

22

Lastpage

23

Abstract

A technique for measuring low-frequency and low-level capacitance variations is proposed. It is based on a lock-in detection circuit with a feedback loop, containing an integrator and a modulator for zeroing the capacitance mean value. This approach provides a good signal-to-noise ratio and high sensitivity. Capacitance variations can be on the order of 100 p.p.m. of the mean value, and the frequency of the variations can be as low as 0.1 Hz. Stray capacitances and the drift due to the environmental conditions are automatically compensated. The measurement technique, experimental apparatus, and initial results are described. Small variations, about 10 fF, have been measured in the presence of 10-pF mean value.<>

Keywords

capacitance measurement; electric sensing devices; 10 pF; automatic compensation; capacitance mean value; capacitance variations; drift; environmental conditions; feedback loop; integrator; lock-in detection circuit; modulator; sensitivity; signal-to-noise ratio; stray capacitance; Capacitance measurement; Capacitors; Electrodes; Feedback circuits; Feedback loop; Frequency; Integrated circuit measurements; Signal to noise ratio; Voltage; Voltage-controlled oscillators;

fLanguage

English

Publisher

ieee

Conference_Titel

Precision Electromagnetic Measurements, 1990. CPEM '90 Digest., Conference on

Conference_Location

Ottawa, Ontario, Canada

Type

conf

DOI

10.1109/CPEM.1990.109906

Filename

109906