Bp 25 en
Processing circuit for differential capacitive sensors
Author: Milan Anderle
This work describes design and implementation of a measuring circuit based on demodulator AD 630 for 2D capacitive position sensor. The key blocks of the measuring circuit are harmonic generator for amplitude modulation and the demodulator AD 630 for consequent demodulation of the sensor output. The measuring circuit includes additional filters to improve signal to noise ratio and correction of phase and offset of the sensor output. The circuit has been connected to PC via multifunction IO card MF 614. A Simulink schematic has been built that allows for comfortable selection of the measured direction and access of the measured position. The measurement setup has been tested on capacitive trimms and a characteristic of a simple capacitive position sensor has been measured, too.