A simple interface circuit to measure very small capacitance changes in capacitive sensors

This paper presents an easy-to-design interface circuit to measure very small-percentage capacitance variations in capacitive sensors, especially suitable for industrial measurements. A computer-controlled 24-bit A/D converter is employed to obtain a higher resolution. This interface circuit can be...

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Bibliographic Details
Published in:IEEE transactions on instrumentation and measurement 2001-12, Vol.50 (6), p.1583-1586
Main Authors: Preethichandra, D.M.G., Shida, K.
Format: Article
Language:English
Subjects:
Capacitance
Capacitance measurement
Capacitive sensors
Capacitors
Circuit design
Circuit testing
Circuits
Converters
Coupling circuits
Error detection
Impedance
Instrumentation
Joining
Laboratories
Monitoring
Probes
Resistors
Sensors
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Summary:This paper presents an easy-to-design interface circuit to measure very small-percentage capacitance variations in capacitive sensors, especially suitable for industrial measurements. A computer-controlled 24-bit A/D converter is employed to obtain a higher resolution. This interface circuit can be used with various types of capacitive sensors. The most interesting thing is, that the measurement results through this interface circuit are independent of the initial capacitance of the sensor. In addition, the double differential operating principle used here minimizes the error caused by coupling and stray capacitance of sensor probes. The operating principle of the designed interface circuit, the major assumptions made, test data, and possible future developments are discussed.
ISSN:0018-9456
1557-9662
DOI:10.1109/19.982949