MEMS Gyroscopes Based on Piezoresistive NEMS Detection of Drive and Sense Motion

This paper presents yaw and pitch microelectromechanical system gyroscopes embedding four active nanoelectromechanical (NEMS) piezoresistive gauges each, two of which are used for differential sensing of the Coriolis motion, and two of which are innovatively used to sense the drive motion and thus to close the drive oscillation loop. After presenting the devices design, this paper discusses the advantages of this particular implementation in terms of operating voltages, electrical equivalent model, and temperature behavior of the scale factor. In operation with voltages lower than 1.8 V without voltage boosting, the devices show sub mdps/√Hz noise density within areas of about 1 mm
²
per device at 0.2-mbar package pressure. Under temperature sweeps, a 3.7-fold better immunity of the scale factor stability is obtained, compared with a similar gyroscope embedding combs (and not NEMS) for drive detection.