A tunable digitally operated MEMS accelerometer

This work presents the concept as well as fabrication and measurement results for a new MEMS accelerometer design that can be operated directly by a digital processor without the need for an analog front end. Elimination of the analog front end for such digitally operated accelerometers can significantly lower the sensor power consumption. The accelerometer consists of a proof mass and a number of parallel plate electrostatic actuators that can be turned "ON" and "OFF" in a sequential manner by a digital controller. Consequently an "ON" or "OFF" output is provided for each input condition based on an output electrode making contact with the biased proof mass. Following a simple switching algorithm, a binary search can be performed by the digital controller to find the acceleration as a binary number. This paper also demonstrates an example of such an accelerometer successfully operated in the zero to 1g range with a 2-bit resolution. The same device concept and configuration can be enhanced to higher number of bits.