Holistic System Modeling of Capacitive Sensors: From Sensor Circuitry to Calibration

摘要

Capacitive sensing technology requires engineering know how in many aspects. Besides the design of the capacitive probe, where the measurement capacitance is modulated by the measurand, capacitive sensing requires dedicated circuitry for capacitance measurement, model based signal evaluation and calibration techniques to draw traceable conclusions. A holistic design framework is required considering all components and their mutual interactions to achieve an appropriate figure of merit as e.g. SNR, resolution or ENOB. With the progress in capacitive sensing for consumer electronics, several integrated solutions for capacitive measurements came up, which offer interesting options for capacitive sensor design. A remarkable simple method is the capacitive voltage divider (CVD) method. In this paper we demonstrate a holistic design approach for a capacitive distance sensor and investigate the CVD principle within the framework.