A Highly Linear Amp-Less Interface Circuit for Capacitive Sensors with ΔΣ C-DAC

Abstract

This paper proposes a low power amp-less interface circuit for capacitive sensors. In the proposed circuit, the charge on the sensor capacitance is compared to the charge on the reference capacitance and converted to a digital value by SAR logic. The proposed circuit can achieve high linearity by using a 1-bit digital ΔΣ modulator and single reference capacitance. The effectiveness of the proposed system was demonstrated by system simulation.