A high sensitivity conditioning circuit for capacitive sensors including stray effects compensation and dummy sensors approach

Abstract

A signal conditioning circuit for capacitive sensors, with high sensitivity and high linearity, is reported here. It is suitable for the measurement of small capacitive values and very small capacitance variations, and therefore it finds potential application in the capacitive characterization of novel material dielectric properties and in sensors exploiting such properties. In the proposed circuit, we make use of a particular configuration of current-to-voltage converter and of an impedance converter, which is adopted to compensate for the standing capacitance value of the sensor, and then to achieve high sensitivity to small capacitance variations. The presented topology is also suitable for the use in differential approaches where a dummy sensor is adopted to filter out unwanted interfering and modifying signals. The design, simulation and experimental characterization of the proposed circuit are reported here.