A LOW-POWER GENERIC INTERFACE CIRCUIT FOR CAPACITIVE SENSORS

This paper presents a low-power generic interface circuit compatible with smart microsystems and capable of interfacing with a large variety of capacitive sensors. The interface chip is highly programmable, can communicate with an external microcontroller over a standard sensor bus, supports sensor self-test, and includes a temperature sensor. The circuit can interface with up to six external sensors and contains three programmable internal reference capacitors in the range of 0.15-8pF. The chip measures 3.2mm x 3.2mm in a standard 3µm single-metal double-poly p-well process, dissipates less than 2.2mW from a single 5V supply and can resolve input capacitance variations of less tha