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US 11,789,036 B2Granted
Real-time isolation of self-test and linear acceleration signals
AssigneeInvenSense, Inc.
InventorsKevin Hughes, Giacomo Laghi, Vito Avantaggiati
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Abstract
A MEMS accelerometer includes proof masses that move in-phase in response to a sensed linear acceleration. Self-test drive circuitry imparts an out-of-phase movement onto the proof masses. The motion of the proof masses in response to the linear acceleration and the self-test movement is sensed as a sense signal on common sense electrodes. Processing circuitry extracts from a linear acceleration signal corresponding to the in-phase movement due to linear acceleration and a self-test signal corresponding to the out-of-phase movement due to the self-test drive signal.
Claims20
A microelectromechanical (MEMS) accelerometer, comprising:
- a first proof mass;
- a second proof mass;
- one or more first electrodes located adjacent to the first proof mass to sense movement of the first proof mass along a first axis in response to a linear acceleration along the first axis during a self-test time period;
- one or more second electrodes located adjacent to the second proof mass to sense movement of the second proof mass along the first axis during the self-test time period, wherein the first proof mass and the second proof mass move in-phase along the first axis in response to the linear acceleration along the first axis;
- self-test drive circuitry coupled to the first proof mass and the second proof mass, wherein the self-test drive circuitry is configured to continuously cause the first proof mass and the second proof mass to move out-of-phase along the first axis during the self-test time period;
- and
- sensing circuitry coupled to receive a sense signal from the one or more first electrodes and the one or more second electrodes, wherein the sensing circuitry outputs a self-test signal corresponding to the out-of-phase movement of the proof masses during the self-test time period, without a linear acceleration signal portion in the presence of linear acceleration.
4 more elements
A microelectromechanical (MEMS) accelerometer, comprising:
- a first proof mass;
- a second proof mass;
- one or more first electrodes located adjacent to the first proof mass to sense movement of the first proof mass along a first axis in response to a linear acceleration along the first axis during a self-test time period;
- one or more second electrodes located adjacent to the second proof mass to sense movement of the second proof mass along the first axis during the self-test time period, wherein the first proof mass and the second proof mass move in-phase along the first axis in response to the linear acceleration along the first axis;
- self-test drive circuitry coupled to the first proof mass and the second proof mass, wherein the self-test drive circuitry is configured to continuously cause the first proof mass and the second proof mass to move out-of-phase along the first axis during the self-test time period;
- and
- sensing circuitry coupled to receive a sense signal from the one or more first electrodes and the one or more second electrodes, wherein the sensing circuitry outputs a linear acceleration signal corresponding to the in-phase movement of the proof masses during the self-test time period, without a self-test signal portion in the presence of the self-test drive circuitry continuously causing the first proof mass and the second proof mass to move out-of-phase.
4 more elements
A microelectromechanical (MEMS) accelerometer, comprising:
- a first proof mass;
- a second proof mass;
- one or more first electrodes located adjacent to the first proof mass to sense movement of the first proof mass along a first axis in response to a linear acceleration along the first axis during a self-test time period;
- one or more second electrodes located adjacent to the second proof mass to sense movement of the second proof mass along the first axis during the self-test time period, wherein the first proof mass and the second proof mass move in-phase along the first axis in response to the linear acceleration along the first axis;
- self-test drive circuitry coupled to the first proof mass and the second proof mass, wherein the self-test drive circuitry is configured to continuously cause the first proof mass and the second proof mass to move out-of-phase along the first axis during the self-test time period;
- and
- processing circuitry coupled to the one or more first electrodes and the one or more second electrodes, wherein the processing circuitry is configured to receive a sense signal during the self-test time period and to extract from the sense signal a self-test signal corresponding to the out-of-phase movement of the proof masses during the self-test time period and a linear acceleration signal corresponding to the in-phase movement of the proof masses during the self-test time period, and wherein the self-test signal does not include a response to an external vibration applied to the MEMS accelerometer.
4 more elements
Dependencies are inferred from the claim text.