Residual voltage self test
    1.
    发明授权

    公开(公告)号:US10564179B2

    公开(公告)日:2020-02-18

    申请号:US15363242

    申请日:2016-11-29

    Abstract: 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.

    Identification of a seal failure in MEMS devices

    公开(公告)号:US10041854B2

    公开(公告)日:2018-08-07

    申请号:US15258720

    申请日:2016-09-07

    Abstract: A microelectromechanical sensor (MEMS) package includes a gyroscope and an accelerometer. The gyroscope is located within a low-pressure cavity that is sealed from an external pressure. The accelerometer is located within a cavity, and the seal for the accelerometer cavity is entirely within the gyroscope cavity. Under normal operating conditions, the accelerometer seal holds the accelerometer cavity at a higher pressure than the pressure of the enclosing gyroscope cavity. In the event that one of the gyroscope seal or the accelerometer seal is broken, the gyroscope senses the change in pressure and a failure is identified.

    Single circuit fault detection
    3.
    发明授权

    公开(公告)号:US10830816B2

    公开(公告)日:2020-11-10

    申请号:US15471539

    申请日:2017-03-28

    Abstract: A fault detection system on a circuit can detect a fault on the same circuit without using a duplicate circuit. A test signal can be generated based on an input signal, and the input signal and test signal can be sent through the circuit and the resulting signals can be compared to determine if any fault is present. In an embodiment, a function can be applied to bits of the input signal and bits of the test signal such that when the signals are compared after passing through the processing block that is to be tested, if the variation between the signals is above a predetermined amount, it can be determined that a fault has occurred. In other embodiments, a first function can be applied to the input signal, and a second function can be applied to the test signal, and the resulting outputs can be compared.

    Accelerometer sense path self-test

    公开(公告)号:US10379137B2

    公开(公告)日:2019-08-13

    申请号:US15363404

    申请日:2016-11-29

    Abstract: 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 difference frequencies. A portion of a sensed signal at the sense drive frequency is used to determine linear acceleration while a portion of the sensed signal at the auxiliary drive frequency is used to identify damage within a sense path from the proof mass.

    MEMS sensor with voltage sensing of movable mass

    公开(公告)号:US10119834B2

    公开(公告)日:2018-11-06

    申请号:US15258939

    申请日:2016-09-07

    Abstract: A suspended spring-mass system is suspended from a plurality of the anchoring points. A source voltage is provided from one of anchoring points to the suspended spring-mass system. The other anchoring points have measurement nodes which measure the voltage at those anchoring points. If a voltage other than the source voltage is received at one of the measurement nodes, an error is identified.

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