Characterization of a configurable sensor signal conditioning circuit for multi-sensor microsystems

This paper describes the sensor signal conditioning circuitry within a transducer interface chip containing a digital communication interface, configuration memory, and programmable analog and digital outputs for actuator control. The highly configurable sensor readout circuits provide front-end signal conditioning for a wide range of capacitive, resistive, voltage, and current output devices. The mixed-mode interface supports up to eight sensors simultaneously and is ideally suited for multi-sensor microsystems. The circuit provides high resolution for each readout mode, including less than 1 fF for capacitive sensors, and introduces a versatile bridge circuit for single element, half-bridge, or full-bridge resistive sensors. Operation ranges for the configurable interfaces are reported along with the performance specifications for the fully functional 2.2×2.2 mm chip, fabricated in 0.5 μm CMOS.