Stmicroelectronics S.r.l.

Invensense, Inc.

Maxim Integrated Products, Inc.

Panasonic Corporation

Hanking Electronics, Ltd.

Luca Coronato

Gabriele Cazzaniga

Giacomo Gafforelli

Sarah Zerbini

Adolfo Giambastiani

Jaakko Ruohio

Barbara Simoni

Alessandro Balzelli Ludovico

Luciano Prandi

Federico Mazzarella

Massimiliano Musazzi

Giacomo Laghi

Michele Folz

Giacomo Calcaterra

Roberto Martini

Matthew Julian Thompson

Carlo Caminada

Angelo Merassi

Manuel Santoro

Demetre Kondylis

Varun Subramaniam Kumar

Antonio Molfese

Pietro Scafidi

Damiano Milani

Gabrielle Cazzaniga

Luigi Esposito

Mrigank Sharma

Edoardo Belloni

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 microelectromechanical (MEMS) sensor, such as an accelerometer, has one more proof masses that respond to movement of the sensor, the movement of which is measured based on a distance between the one or more proof masses and on one or more sense electrodes. The accelerometer also has a plurality of auxiliary electrodes and a signal generator configured to apply an auxiliary signal having a first harmonic frequency to the plurality of auxiliary electrodes. Circuitry receives a sensed signal from the plurality of sense electrodes and identifies a portion of the sensed signal having the first harmonic frequency. Based on this identified portion of the sensed signal, the circuitry determines whether a residual voltage is present on the one or more proof masses or on the one or more sense electrodes, and the circuitry modifies the operation of the accelerometer when the residual voltage is determined to be present in order to compensate for the residual voltage.

MEMS sensor with compensation of residual voltage

A microelectromechanical system (MEMS) test structure includes a plurality of capacitors formed from sense electrodes and capacitive plates having a predetermined geometry and size associated with a related MEMS device such as a MEMS sensor. Based on the predetermined relationships between the capacitors of the test structure, and between the test structure and the MEMS devices, an effect of fringing fields on the sensed capacitances of the MEMS devices may be eliminated, and the capacitive gap of the MEMS device may be accurately measured.

Capacitance gap measurement

A MEMS gyroscope includes a driven mass that moves in response to a drive force. A drive amplitude sense electrode is included as a feature of the drive mass and extends in a direction perpendicular to the drive direction. A change in capacitance is measured based on the relative location of the drive amplitude sense electrode to a known fixed position, which in turn is used to accurately determine a location of the driven mass.

Robust method for gyroscope drive amplitude measurement

A MEMS sensor includes a central anchoring region that maintains the relative position of an attached proof mass relative to sense electrodes in the presence of undesired forces and stresses. The central anchoring region includes one or more first anchors that rigidly couple to a cover substrate and a base substrate. One or more second anchors are rigidly coupled to only the cover substrate and are connected to the one or more first anchors within the MEMS layer via an isolation spring. The proof mass in turn is connected to the one or more second anchors via one or more compliant springs.

MEMS design with shear force rejection for reduced offset

A gyroscope includes drive portions, lever arms, and proof masses located in a device plane. The lever arms are caused to rotate about an anchoring point based on anti-phase movement of the drive portions along a first axis in the device plane, and are coupled to the proof masses to cause the proof masses to move in anti-phase along an axis perpendicular to the first axis in the device plane. In response to a Coriolis force applied to the proof masses, the lever arm rotates out of plane and the proof masses move relative to sense electrodes. The movement of the proof masses with respect to the sense electrodes is used to measure angular velocity.

Out-of-plane sensing gyroscope robust to external acceleration and rotation

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 optimal demodulation phase for extracting an in-phase component of a MEMS gyroscope output signal is determined through a test procedure. During the test procedure, multiple different rotation rate patterns such as different directions of rotation and different rotation rates are applied to the MEMS gyroscope while the MEMS gyroscope output signal is demodulated based on demodulation phases near a predicted quadrature phase for the MEMS gyroscope. The measured gyroscope outputs are used to calculate an optimal demodulation phase for the MEM gyroscope.

Robust method for tuning of gyroscope demodulation phase

An integrated MEMS structure includes a driving assembly anchored to a substrate and actuated with a driving movement. A pair of sensing masses suspended above the substrate and coupled to the driving assembly via elastic elements is fixed in the driving movement and performs a movement along a first direction of detection, in response to an external stress. A coupling assembly couples the pair of sensing masses mechanically to couple the vibration modes. The coupling assembly is formed by a rigid element, which connects the sensing masses and has a point of constraint in an intermediate position between the sensing masses, and elastic coupling elements for coupling the rigid element to the sensing masses to present a first stiffness to a movement in phase-opposition and a second stiffness, greater than the first, to a movement in phase, of the sensing masses along the direction of detection.

Microelectromechanical structure with enhanced rejection of acceleration noise

A microelectromechanical (MEMS) accelerometer has a proof mass, a sense electrode, and an auxiliary electrode. The sense electrode is located relative to the proof mass such that a capacitance formed by the sense electrode and the proof mass changes in response to a linear acceleration along a sense axis of the accelerometer. The auxiliary electrode is located relative to the proof mass such that a capacitance formed by the auxiliary electrode and proof mass is static in response to the linear acceleration. A sense drive signal is applied at the sense electrode and an auxiliary drive signal is applied at the auxiliary electrode. The sense drive signal and the auxiliary drive signal have different frequencies. An error is identified based on a portion of a signal that is received from the accelerometer and that is responsive to the auxiliary drive signal. Compensation is performed at the accelerometer based on the identified error.

Identification and compensation of MEMS accelerometer errors

A gyroscope includes four drive masses and four sense masses. Each drive mass is adjacent to two other drive masses and opposite the fourth drive mass, and each sense mass is adjacent to two other sense masses and opposite the fourth sense mass. Each drive mass may oscillate in a manner that is perpendicular to its adjacent drive mass and parallel and anti-phase to its opposite mass. The sense motion of the each sense mass may be coupled in a manner that prevents motion due to linear acceleration or angular acceleration.

Yaw rate gyroscope robust to linear and angular acceleration

A MEMS sensor includes a substrate and a MEMS layer. A plurality of anchoring points within the MEMS layer suspend a suspended spring-mass system that includes active micromechanical components that respond to a force of interest such as linear acceleration, angular velocity, pressure, or magnetic field. Springs and rigid masses couple the active components to the anchoring points, such that displacements of the anchoring points do not substantially cause the active components within the MEMS layer to move out-of-plane.

Anchoring structure for a sensor insensitive to anchor movement

A sensor such as an accelerometer includes a proof mass located opposite a plurality of electrodes located on a substrate. Some of the electrodes are auxiliary electrodes that apply an alternating current auxiliary signal to the proof mass while other electrodes are sense electrodes that sense movement of the proof mass. When a residual voltage is not present on the proof mass or on the sense electrodes, the forces imparted by the auxiliary signal onto the proof mass are substantially balanced. When the residual voltage is present on the proof masses, forces at a first harmonic frequency of the auxiliary signal are sensed by a sense electrode of the sensor. A self-test is failed if the sensed forces exceed a threshold.

Residual voltage self test

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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Corsico, Italy

Luca Coronato