A switched-capacitor interface for capacitive pressure sensors

A switched-capacitor interface of a capacitive pressure sensor is developed which provides linear digital outputs. It consists of a sample/hold circuit followed by a charge-balancing analog-to-digital converter. Two linearization methods based on the hyperbolic relation between the sensor capacitance and pressure are investigated in order to accommodate them to the basic interface configuration. In either method, linear digital outputs with an accuracy higher than 8-b are obtained. Because of its high accuracy and compatible fabrication process, the interface described is best suited for a smart silicon capacitive pressure sensor