Ultra-Low Power Digitally Operated Tunable MEMS Accelerometer

Abstract

This paper presents the concept as well as fabrication and measurement results for a new class of MEMS accelerometers 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. Furthermore, this paper also estimates the operating power consumption for such an accelerometer. A simple 2-b version of such accelerometers has been successfully fabricated and operated in the 0-1-g range. The same device concept and the configuration can be enhanced to higher number of bits.