Improving the temperature stability of mems gyroscope bias with on-chip stress sensors

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 degrees 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.