Invensense, Inc.

Roberto Martini

Luca Coronato

Matthew Julian Thompson

Giacomo Laghi

Jaakko Ruohio

Xian Huang

A dual axis accelerometer with a single proof mass measures in-plane acceleration (e.g., either along an x-axis or a y-axis), out-of-plane acceleration (e.g., normal to an x-y plane), and tilt of a fixed portion of a MEMS layer (e.g., normal to the x-y plane). In response to a tilt measurement, the dual-axis accelerometer compensates any offset (e.g., variability) of the out-of-plane accelerometer in order to maintain offset stability. In some embodiments, multiple dual axis accelerometers, perpendicularly configured, may be implemented via processing circuitry to offer three axis sensitivity capability.

Dual axis accelerometer with compensation electrodes

A MEMS sensor may include multiple sense electrodes located relative to respective portions of one or more proof masses of a MEMS layer of the sensor. Individual sense electrodes are capable of individual calibration within the drive and/or sense path for the sense electrode. A distance between each individual sense electrode relative to a proof mass is determined for the at-rest state of the sensor. Calibration values are determined based on these distances, and individual drive and/or sense signals associated with each sense electrode are modified to adjust for changes in distance, such as are caused by shifting, tilting, or bending of the MEMS layer or substrate.

MEMS strain sensitivity calibration

Exemplary embodiment of a tilting z-axis, out-of-plane sensing MEMS accelerometers and associated structures and configurations are described. Disclosed embodiments facilitate improved offset stabilization. Non-limiting embodiments provide exemplary MEMS structures and apparatuses characterized by one or more of having a sensing MEMS structure that is symmetric about the axis orthogonal to the springs or flexible coupling axis, a spring or flexible coupling axis that is aligned to one of the symmetry axes of the electrodes pattern, a different number of reference electrodes and sense electrodes, a reference MEMS structure having at least two symmetry axes, one which is along the axis of the springs or flexible coupling, and/or a reference structure below the spring or flexible coupling axis.

MEMS structure for offset minimization of out-of-plane sensing accelerometers

An exemplary sensor may include a MEMS layer anchored to a cap and a substrate by anchoring portions of the MEMS layer. A suspended spring-mass system may include springs, at least one rigid mass, and at least one movable mass. The anchoring springs may be torsionally compliant about one or more axes and coupled to the rigid mass such that forces imparted by the anchoring portions are not transmitted to the movable mass.

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Milan, Italy

Roberto Martini