Abstract: A gyroscopic sensor system can include a proof mass, which can be configured to vibrate in a first primary mode and a second primary mode, where the first primary mode can be driven into resonance, where an in-phase signal can be induced in the second primary mode in response to a rotation of the gyroscopic sensor system. The gyroscopic sensor system can also include a quadrature force circuit, which can be configured to force the second primary mode of the proof mass. The gyroscopic sensor system can also include control circuitry, which can be configured to drive the quadrature force circuit using a quadrature test signal which can be configured to generate a quadrature response in the proof mass that can be in quadrature with the in-phase signal. The control circuitry can also be configured to measure the quadrature response of the proof mass to the quadrature test signal.

Abstract: Microelectromechanical systems (MEMS) capacitive strain gauge sensors are described. The strain gauge sensors include a lever configured to mechanically amplify a strain response. In some embodiments, an anchored beam is coupled to the effort arm of the lever and a movable sensing finger to the resistance arm. The effort arm may be shorter than the resistance arm, thus providing a mechanical amplification.

Abstract: Microelectromechanical systems (MEMS) capacitive strain gauge sensors are described. The strain gauge sensors include a lever configured to mechanically amplify a strain response. In some embodiments, an anchored beam is coupled to the effort arm of the lever and a movable sensing finger to the resistance arm. The effort arm may be shorter than the resistance arm, thus providing a mechanical amplification.

Abstract: Techniques for self-testing of microelectromechanical systems (MEMS) inertial sensors are described. Some techniques involve testing inertial sensor characteristics such as an accelerometer's sensitivity to acceleration and a gyroscope's sensitivity to angular motion. The tests may be performed by providing a test signal, which simulates a stimulus such as an acceleration or angular rate, to a MEMS inertial sensor and examining the sensor's output. The efficacy of such self-tests may be impaired by spurious signals, which may be present in the sensor's environment and may influence the sensor's output. Accordingly, the self-testing techniques described herein involve detecting the presence of any such spurious signals and discarding self-test results when their presence is detected. In some embodiments, the presence of spurious signals may be detected using a signal obtained by mixing the response of the MEMS inertial sensor with a reference signal substantially in quadrature with the test signal.

Abstract: Systems and methods for sensing angular motion using a microelectromechanical system (MEMS) gyroscope are described. These systems and methods may be useful for sensing angular motion in the presence of low-frequency noise, which may be noise below 1 KHz. In a system for sensing angular motion, low-frequency noise may give rise to duty cycle jitter, which may affect the demodulation of the sense signal and cause errors in angular motion estimates. The systems and methods described herein address this problem by relying on double-edge phase detection technique that involves sensing when the rising and falling edges of the resonator signal deviate from their expected values in the idealized 50% duty cycle scenario. To prevent the formation of ripples in the double-edge phase detection that may otherwise affect the demodulation of the sense signal, a switch may be used. The switch may be maintained in a non-conductive state when a ripple is received.

Abstract: Sense amplifiers for use in connection with microelectromechanical system (MEMS) gyroscopes are described. The sense amplifiers may be configured to change the level of a gyroscope signal, i.e., the signal produced by a gyroscope in response to angular motion, to a level suitable for processing circuitry arranged to infer the angular velocity. The sense amplifier may further provide a DC discharge path allowing for discharge of the DC component of the output signal. The DC discharge path may include an anti-aliasing filter and a resistive circuit. The anti-aliasing filter may filter the output signal to maintain the resistive circuit in the linear region. The anti-aliasing filter may be designed with a frequency response such that discrete frequency sub-bands are blocked or at least attenuated. The frequency sub-bands may be tuned to substantially match the gyroscope's resonant frequency and its integer multiples.

Abstract: Systems and methods for sensing angular motion using a microelectromechanical system (MEMS) gyroscope are described. These systems and methods may be useful for sensing angular motion in the presence of low-frequency noise, which may be noise below 1 KHz. In a system for sensing angular motion, low-frequency noise may give rise to duty cycle jitter, which may affect the demodulation of the sense signal and cause errors in angular motion estimates. The systems and methods described herein address this problem by relying on double-edge phase detection technique that involves sensing when the rising and falling edges of the resonator signal deviate from their expected values in the idealized 50% duty cycle scenario. To prevent the formation of ripples in the double-edge phase detection that may otherwise affect the demodulation of the sense signal, a switch may be used. The switch may be maintained in a non-conductive state when a ripple is received.

Abstract: Techniques for self-testing of microelectromechanical systems (MEMS) inertial sensors are described. Some techniques involve testing inertial sensor characteristics such as an accelerometer's sensitivity to acceleration and a gyroscope's sensitivity to angular motion. The tests may be performed by providing a test signal, which simulates a stimulus such as an acceleration or angular rate, to a MEMS inertial sensor and examining the sensor's output. The efficacy of such self-tests may be impaired by spurious signals, which may be present in the sensor's environment and may influence the sensor's output. Accordingly, the self-testing techniques described herein involve detecting the presence of any such spurious signals and discarding self-test results when their presence is detected. In some embodiments, the presence of spurious signals may be detected using a signal obtained by mixing the response of the MEMS inertial sensor with a reference signal substantially in quadrature with the test signal.

Abstract: Various embodiments mitigate the risk of frequency-lock in systems having multiple resonators by dynamically changing the frequency at which at least one of the resonators is driven. More particularly, the drive frequency of at least one of the resonators is changed often enough that the multiple resonators do not have time to achieve frequency lock. Changes in the oscillation of the resonators may be analyzed to determine, for example, acceleration of such systems. Some embodiments implement self-test by assessing expected performance of a system with toggling drive frequencies. More particularly, some embodiments implement self-test by artificially inducing displacement of a movable member of a system.

Abstract: Sense amplifiers for use in connection with microelectromechanical system (MEMS) gyroscopes are described. The sense amplifiers may be configured to change the level of a gyroscope signal, i.e., the signal produced by a gyroscope in response to angular motion, to a level suitable for processing circuitry arranged to infer the angular velocity. The sense amplifier may further provide a DC discharge path allowing for discharge of the DC component of the output signal. The DC discharge path may include an anti-aliasing filter and a resistive circuit. The anti-aliasing filter may filter the output signal to maintain the resistive circuit in the linear region. The anti-aliasing filter may be designed with a frequency response such that discrete frequency sub-bands are blocked or at least attenuated. The frequency sub-bands may be tuned to substantially match the gyroscope's resonant frequency and its integer multiples.

Abstract: A microelectromechanical system (MEMS) accelerometer is described. The MEMS accelerometer is arranged to limit distortions in the detection signal caused by displacement of the anchor(s) connecting the MEMS accelerometer to the underlying substrate. The MEMS accelerometer may include masses arranged to move in opposite directions in response to an acceleration of the MEMS accelerometer, and to move in the same direction in response to displacement of the anchor(s). The masses may, for example, be hingedly coupled to a beam in a teeter-totter configuration. Motion of the masses in response to acceleration and anchor displacement may be detected using capacitive sensors.

Abstract: Various embodiments mitigate the risk of frequency-lock in systems having multiple resonators by dynamically changing the frequency at which at least one of the resonators is driven. More particularly, the drive frequency of at least one of the resonators is changed often enough that the multiple resonators do not have time to achieve frequency lock. Changes in the oscillation of the resonators may be analyzed to determine, for example, acceleration of such systems. Some embodiments implement self-test by assessing expected performance of a system with toggling drive frequencies. More particularly, some embodiments implement self-test by artificially inducing displacement of a movable member of a system.

Abstract: A microelectromechanical systems (MEMS) accelerometer is described. The MEMS accelerometer may comprise a proof mass configured to sense accelerations in a direction parallel the plane of the proof mass, and a plurality of compensation structures. The proof mass may be connected to one or more anchors through springs. The compensation structures may be coupled to the substrate of the MEMS accelerometer through a rigid connection to respective anchors. A compensation structure may comprise at least one compensation electrode forming one or more lateral compensation capacitors. The compensation capacitor(s) may be configured to sense displacement of the anchor to which the compensation structures is connected.

Abstract: Various embodiments mitigate the risk of frequency-lock in systems having multiple resonators by dynamically changing the frequency at which at least one of the resonators is driven. More particularly, the drive frequency of at least one of the resonators is changed often enough that the multiple resonators do not have time to achieve frequency lock. Changes in the oscillation of the resonators may be analyzed to determine, for example, acceleration of such systems. Some embodiments implement self-test by assessing expected performance of a system with toggling drive frequencies. More particularly, some embodiments implement self-test by artificially inducing displacement of a movable member of a system.

Abstract: A microelectromechanical system (MEMS) accelerometer is described. The MEMS accelerometer is arranged to limit distortions in the detection signal caused by displacement of the anchor(s) connecting the MEMS accelerometer to the underlying substrate. The MEMS accelerometer may include masses arranged to move in opposite directions in response to an acceleration of the MEMS accelerometer, and to move in the same direction in response to displacement of the anchor(s). The masses may, for example, be hingedly coupled to a beam in a teeter-totter configuration. Motion of the masses in response to acceleration and anchor displacement may be detected using capacitive sensors.

Abstract: An accelerometer has a movable mass suspended above a substrate, and a variable acceleration capacitor supported by the substrate. The movable mass has a mass anchor securing the mass to the substrate, while the acceleration capacitor has both a stationary finger extending from the substrate, and a movable finger extending from the movable mass. The accelerometer also has a variable stress capacitor, which also includes the stress finger, for determining movement of the mass anchor relative to the substrate.

Abstract: A microelectromechanical systems (MEMS) accelerometer is described. The MEMS accelerometer may comprise a proof mass configured to sense accelerations in a direction parallel the plane of the proof mass, and a plurality of compensation structures. The proof mass may be connected to one or more anchors through springs. The compensation structures may be coupled to the substrate of the MEMS accelerometer through a rigid connection to respective anchors. A compensation structure may comprise at least one compensation electrode forming one or more lateral compensation capacitors. The compensation capacitor(s) may be configured to sense displacement of the anchor to which the compensation structures is connected.

Abstract: Various embodiments mitigate the risk of frequency-lock in systems having multiple resonators by dynamically changing the frequency at which at least one of the resonators is driven. More particularly, the drive frequency of at least one of the resonators is changed often enough that the multiple resonators do not have time to achieve frequency lock. Changes in the oscillation of the resonators may be analyzed to determine, for example, acceleration of such systems. Some embodiments implement self-test by assessing expected performance of a system with toggling drive frequencies. More particularly, some embodiments implement self-test by artificially inducing displacement of a movable member of a system.

Abstract: A MEMS sensor includes a micro-electromechanical structure, a detection circuit, and a self-test circuit to test the health of the MEMS sensor during runtime operations. The self-test circuit is configured to inject into the micro-electromechanical structure a plurality of injected test signals that are broad-band frequency-varying frequency signals, which are based on spread spectrum based modulation. The injected test signals may a magnitude that is below an observable threshold of the sensor signal as well as a test-signal bandwidth that overlaps with a substantial portion of the sensor bandwidth, including the stimulus of interest.

Abstract: An accelerometer has a movable mass suspended above a substrate, and a variable acceleration capacitor supported by the substrate. The movable mass has a mass anchor securing the mass to the substrate, while the acceleration capacitor has both a stationary finger extending from the substrate, and a movable finger extending from the movable mass. The accelerometer also has a variable stress capacitor, which also includes the stress finger, for determining movement of the mass anchor relative to the substrate.