Finding Solutions to the Sensor Drift Problem
By
DR. ERDINC TATAR (Analog Devices, Inc., Wilmington, MA)
The seminar will be on Monday, April 16, 2018 at 10:45 @ EE-314
Abstract
One major performance limiting problem that is common among most of the sensors is the drift. Environmental stress and temperature effects are believed to be the major source of the drift and the latter is studied the most in the literature. Certain enhancements are achieved but the sensor drift cannot be removed completely by temperature compensation. In this talk a solution methodology is proposed for the drift problem by incorporating the stress sensor and the gyroscope on the same die for the first time. Towards that end, a simulation methodology that couples finite element analysis and circuit solver has been developed to understand the stress-zero rate output (ZRO) relation and stress tests have been performed on an in-house fabricated and vacuum packaged SOI-MEMS gyroscope. Through ovenization it is demonstrated that stress compensation suppresses the long term drift by seven fold. Since stress compensation achieved promising results, this work is extended by designing better on-chip stress sensors, investigating the die stress with different die attaches and die mount techniques, and applying stress compensation to other sensors.
High drive displacement improves the signal to noise ratio of a resonator but also leads to a nonlinear force displacement behavior that is observable as a hysteresis in the frequency-phase and frequency-amplitude relations. These nonlinearities lead to Amplitude-frequency (A-f) effect where resonance frequency depends on the displacement. A cubically shaped nonlinearity tuning comb finger design that cancels the inherent softening nonlinearity of the gyroscope drive mode is proposed by introducing a DC voltage controlled hardening nonlinearity. The functionality of the fingers was demonstrated and cancelling drive nonlinearities resulted in a better bias instability compared to the high displacement with nonlinear characteristics.
Bio: Dr. Erdinç Tatar received B.S. and M.S. degrees (with high honors) in Electrical and Electronics Engineering from Middle East Technical University (METU), Ankara, Turkey, and Ph.D. degree in Electrical and Computer engineering from Carnegie Mellon University, in 2008, 2010, and 2016, respectively. He was a Graduate Research Assistant with Micro-Electro-Mechanical Systems Research and Applications Center, METU, and with Carnegie Mellon University from 2008 to 2011, and 2012 to 2016, respectively. He is currently a MEMS Design Engineer responsible for the development of next generation gyroscopes within the MEMS Advanced Technology Development Group in Analog Devices, Inc., Wilmington, MA. His research interests include MEMS sensors, microfabrication and packaging technologies, and readout and control electronics for MEMS sensors.