Derek Shaeffer

MEMS inertial sensors: A tutorial overview

Inertial sensors based on MEMS technology are fast becoming ubiquitous with their adoption into many types of consumer electronics products, including smart phones, tablets, gaming systems, TV remotes, toys, and even (more recently) power tools and wearable sensors. Now a standard feature of most smart phones, MEMS-based motion tracking enhances the user interface by allowing response to user motions, complements the GPS receiver by providing dead-reckoning indoor navigation and supporting location-based services, and holds the promise of enabling handset optical image stabilization in next-generation handsets by virtue of its lower cost and small form factor. This tutorial provides an overview of MEMS technology and describes the essential features of the mechanical systems underlying the most common sensors accelerometers and gyroscopes. It also highlights some fundamental trade-offs related to mechanical system dynamics, force and charge transduction methods, and their implications for the mixed-signal systems that process the sensor outputs. The presentation of an energy-based metric allows a comparison of the performance of competing sensor solutions. For each type of sensor, descriptions of the underlying mechanical theory, canonical sensor architectures, and key design challenges are also presented. Finally, the tutorial reviews multisensor silicon MEMS/CMOS monolithic integration, which is driving the cost and form factor reduction behind the current proliferation of these devices.