A Transformer-based Front-end Circuit for Grounded Capacitive Sensors with Square-Wave Excitation

HABERMAN, MARCELO A.; SPINELLI, ENRIQUE M.; REVERTER, FERRAN

Lecce

Congreso; Eurosensors XXXIV Conference; 2023

Eurosensors

This work proposes and experimentally characterizes a novel front-end circuit forcapacitive sensors with one electrode grounded, which are quite common in liquid-level andposition measurement applications. The circuit relies on a properly-shielded custom transformer,as already suggested in the literature, but using a square excitation instead of a sinusoidal excitation,thus being a simpler solution. Furthermore, the sensor signal is read by a charge amplifier with asingle supply voltage, instead of a transimpedance amplifier with a split supply voltage. Thepreliminary experimental results show an input-output characteristic with a non-linearity errorlower than 0.5% FSS in the [0, 33] pF measuring range.