Lightweight thermal compensation technique for mems capacitive accelerometer oriented to quasi-static measurements

Abstract

The application of MEMS capacitive accelerometers isimited by its thermal dependence, and each accelerometer must be individually calibrated to improve its performance. In this work, aight calibration method based on theoretical studies is proposed to obtain two characteristic parameters of the sensor’s operation: the temperature drift of bias and the temperature drift of scale factor. This method requiresess data to obtain the characteristic parameters, allowing a faster calibration. Furthermore, using an equation with fewer parameters reduces the computational cost of compensa-tion. After studying six accelerometers, modelIS3DSH, their characteristic parameters are obtained in a temperature range between 15◦C and 55◦C. It is observed that the Temperature Drift of Bias (TDB) is the parameter with the greatest influence on thermal drift, reaching 1.3 mg/◦C. The Temperature Drift of Scale Factor (TDSF) is always negative and ranges between 0 and −400 ppm/◦C. With these parameters, the thermal drifts are compensated in tests with 20◦C of thermal variation. An average improvement of 47% was observed. In the axes where the thermal drift was greater than 1 mg/◦C, the improvement was greater than 80%. Other sensor behaviors have also been analyzed, such as temporal drift (up to 1 mg/h for three hours) and self-heating (2–3◦C in the first hours with the corresponding drift). Thermal compensation has been found to reduce the effect of theatter in the first hours after power-up of the sensor by 43%.