An 8-Bit Digitally Operated Micromachined Accelerometer

Abstract

This work presents successful implementation and characterization of an 8-bit digitally operated micromachined accelerometer. Such device is comprised of an electrostatically tunable acceleration switch with 8 sets of electrostatic tuning electrodes. Similar to bits in a binary number, the tuning force of each electrode set increases by a factor of 2 with respect to the adjacent electrode set. A fabricated device has been interfaced with a micro-controller performing a binary search by controlling state of different tuning electrodes (ON or OFF) to interpret the acceleration with 8 bits of resolution. Measurement results show good agreement between the applied acceleration and the binary acceleration output of the sensor reported by the controller. The tested 8-bit prototype has full-scale acceleration of 2.7g with resolution 10.5 mg s (1/28 of full scale). Requiring only a bias voltage for operation (zero static current) and readout of the switch output (a digital high or low voltage) that can be performed directly by a digital controller, such devices can lead to ultra-low power accelerometers by eliminating the need for an analog-front-end. [2020-0201]