A Modified De Sauty Autobalancing Bridge-Based Interface for Wide-Range Capacitive Sensor Applications

摘要

In the last years, the development of new techniques toward miniaturization and fabrication of higher sensitivity devices has led to the production of a new generation of high-quality sensors for environmental and biological parameters detection [1, 2]. Capacitive sensors have been widely studied, thanks to the easiness of changing their electro-geometrical properties. Bridge-based front ends are typically employed in those applications where the sensing element value shows reduced variations with respect to its baseline. Recent works on resistive sensors [3, 4] have demonstrated that high sensitivity and easy resistive value estimation features of the classical Wheatstone bridge can be improved through the development of an "autobalancing" configuration of the basic bridge, by adding a tunable resistance. The latter, set by a suitable feedback loop, spreads the equilibrium condition over a wider range.