Improving the Temperature Stability of MEMS Gyroscope Bias with on-chip Stress Sensors
Derin Erkan, Erdinc Tatar
Abstract
Temperature calibration is commonly used to suppress the bias drift of MEMS inertial sensors. Temperature compensation reduces the bias drift but cannot eliminate it. We report a compensation technique for temperature-induced drifts by incorporating temperature and on-chip stress, for the first time. Adding on-chip stress to the temperature captures the offset behavior with hysteresis more accurately. Our open and closed-loop sense mode temperature sweep results demonstrate almost three-fold offset stability improvement over only temperature calibration for a wide (65°C) temperature range. Temperature and stress sensors provide data about thermal stress and stress mismatches in the sensor stack, respectively. We validate the calibration concept with a MEMS ring gyroscope integrated with eight capacitive stress sensors. We perform the temperature tests with an on-PCB heater that only heats the MEMS die and front-end amplifiers.