A switched-capacitor interface for capacitive pressure sensors

Abstract

A switched-capacitor interface for a capacitive pressure sensor is developed which provides a linear digital output. It consists basically of a sample/hold circuit followed by a charge-balancing analog-to-digital converter. The sensor capacitance changes hyperbolically with an applied pressure. To convert the nonlinear capacitance change into the linear digital output, two linearization methods are investigated. In either method, a linear digital output with an accuracy higher than 8-b is obtained. Because of its high-accuracy capability and compatible fabrication process, the interface described is best suited for a smart silicon capacitive pressure sensor.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>