High-Linearity Front-End Circuit for Remote Grounded Capacitive Sensors
Marcelo Haberman, Enrique Mario Spinelli, Ferran Reverter
Abstract
This article 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-accuracy reference 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 nonlinearity error below 0.01% when measuring capacitances of units or tens of picofarad, even with up to 12-m interconnecting cables.
Topics & Concepts
Capacitive sensingElectrical engineeringCapacitanceLinearityParasitic capacitanceAmplifierFront and back endsCompensation (psychology)Electronic engineeringEngineeringShielded cableTransformerComputer scienceCMOSVoltagePhysicsMechanical engineeringQuantum mechanicsElectrodePsychologyPsychoanalysisSensor Technology and Measurement SystemsWater Quality Monitoring TechnologiesAnalytical Chemistry and Sensors