High-linearity Front-end Circuit for Remote Grounded Capacitive Sensors

M. HABERMAN; E. SPINELLI; F. REVERTER

IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT

IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC

Lugar: New York; Año: 2021 vol. 70 p. 1 - 8

0018-9456

This paper presents a novel front-end circuit for remote grounded capacitive sensors. The circuit is insensitive to amplifier input capacitance and stray interconnecting-cable capacitances. It does not rely on neutralization or compensation techniques that require manual adjustments and high-accuracyreference components. The proposed solution reduces the circuit input capacitance below a few femptofarads using a simple but properly shielded custom transformer. In addition, the circuit keeps a non-linearity error below 0.01% when measuring capacitances of units or tens of picofarad, even with up to 12 m interconnecting cables.