Achieving long-term bias stability in high-Q inertial MEMS by temperature self-sensing with a 0.5 Millicelcius precision

Abstract

We present long-term bias drift compensation in high-quality (Q) factor MEMS gyroscopes using real-time temperature selfsensing. The approach takes advantage of linear temperature dependence of the drive-mode resonant frequency for selfcompensation of temperature-induced sense-mode drifts. The approach was validated by a vacuum packaged silicon quadruple mass gyroscope, with signal-to-noise ratio (SNR) enhanced by isotopic Q-factors of 1.2 million. Owing to high Q-factors, a measured frequency stability of 0.01 ppm provided a temperature self-sensing precision of 0.0004 °C, on par with the state-of-the-art MEMS resonant thermometers. Real-time self-compensation yielded a total bias error of 0.5 °/hr and total scale-factor error of 700 ppm over temperature variations. This enabled repeatable long-term rate measurements required for MEMS gyrocompassing with a milliradian azimuth precision.