Abstract: An oscillator drive circuit and a trim circuit are implemented inside an integrated circuit of a sensor. The drive circuit provides an oscillating drive signal at a resonant frequency to drive a movable mass of the sensor. The drive circuit includes a phase shift circuit having an input for receiving a first signal indicative of an oscillation of the movable mass and having an output. The phase shift circuit adds a phase shift component to the first signal and produces a second signal shifted in phase by the phase shift component. The trim circuit includes a first comparator for receiving the first signal, a second comparator for receiving the second signal, and a processing element. The processing element determines a phase lag between the first and second signals and produces trim code for use by the phase shift circuit, the trim code being configured to adjust the phase shift component.

Abstract: A sensor interface circuit includes a continuous-time capacitance-to-voltage (C/V) converter having C/V input and output ends, the C/V input end being configured for electrical connection with first and second sense nodes of a capacitive sensor. A filter circuit is electrically coupled to the C/V output ends. The filter circuit has first and second resistors at corresponding first and second filter input ends of the filter circuit, a capacitor connected between first and second filter output ends of the filter circuit, and a chopper circuit interposed between the first and second filter input ends and the first and second filter output ends. A buffer circuit is electrically coupled with the first and second filter output ends of the filter circuit. The filter circuit applies low pass filtering of sense signals from the capacitive sensor before sampling and demodulation operations to reduce high-frequency interference in the sense signals.

Abstract: Systems and methods are provided for continuously monitoring operation of a sensing device, in which the sensing device includes a MEMS gyroscope and a quadrature feedback loop coupled to the MEMS gyroscope, the quadrature feedback loop including a quadrature feedback controller. A test signal generator is configured to generate and apply a test signal to the quadrature feedback loop at an input of the quadrature feedback controller. A fault detector is coupled to an output of the quadrature feedback controller. The fault detector is configured to receive a quadrature feedback signal, detect effects of the test signal in the quadrature feedback signal, and generate a monitor output indicative of the operation of the sensing device base on the detected effects of the test signal.

Abstract: Systems and methods are provided for continuously monitoring operation of a sensing device, in which the sensing device includes a MEMS gyroscope and a quadrature feedback loop coupled to the MEMS gyroscope, the quadrature feedback loop including a quadrature feedback controller. A test signal generator is configured to generate and apply a test signal to the quadrature feedback loop at an input of the quadrature feedback controller. A fault detector is coupled to an output of the quadrature feedback controller. The fault detector is configured to receive a quadrature feedback signal, detect effects of the test signal in the quadrature feedback signal, and generate a monitor output indicative of the operation of the sensing device base on the detected effects of the test signal.

Abstract: A sensor system includes first and second capacitive sensors. An excitation circuit, coupled with the sensors, applies an excitation voltage to each of the sensors. The excitation voltage is characterized by a first, second, and third excitation voltage components, wherein the second and third excitation voltage components have opposite polarities. A capacitance-to-voltage (C/V) converter, electrically coupled with the sensors, generates a differential-mode output signal in response to the first excitation voltage component applied to the sensors, and the C/V converter generates a common-mode output signal in response to the second and third excitation voltage components applied to the sensors.

Abstract: A micro-electromechanical systems (MEMS) transducer (100, 700) is adapted to use lateral axis vibration to generate non-planar oscillations in a pair of teeter-totter sense mass structures (120/140, 720/730) in response to rotational movement of the transducer about the rotation axis (170, 770) with sense electrodes connected to add pickups (e.g., 102/107, 802/807) diagonally from the pair of sense mass structures to cancel out signals associated with rotation vibration.

Abstract: Systems and methods are provided for monitoring operation of MEMS accelerometers (100). In these embodiments a control loop (112) having a forward path (114) is coupled a MEMS transducer (110), and a test signal generator (124) and test signal detector (126) is provided. The test signal generator (124) is configured to generate a test signal and apply the test signal to the forward path (114) of the control loop (112) during operation of the MEMS accelerometer transducer (110). The test signal detector (126) is configured to receive an output signal from the control loop and detect the effects of the test signal in the output signal. Finally, the test signal detector (126) is further configured to generate a monitor output indicative of the operation of the sensing device to provide for the continuous monitoring of the operation of the MEMS accelerometer (100).

Abstract: A multi-mass resonator and a common-mode detection circuit are provided. The common-mode detection circuit, for example, may include a plurality of sensing electrodes, an interface circuit configured to interface with the plurality of sensing electrodes, and a common-mode capacitance extractor circuit electrically coupled in parallel to the interface circuit and configured to detect common-mode capacitance between the plurality of sensing electrodes and output a voltage representative the detected common-mode capacitance, and a differential-mode capacitance extractor circuit electrically coupled in parallel to the interface circuit and configured to detect differential-mode capacitance between the plurality of sensing electrodes and output a voltage representative the detected differential-mode capacitance.

Abstract: An inertial sensor (20) includes a movable element (24) coupled to a substrate (28) and adapted for motion about a rotational axis (34). The sensor (20) further includes a trim elements (36, 38). The trim elements (36, 38) are spaced away from a surface (26) of the substrate (28) and are symmetrically positioned on opposing sides of the rotational axis (34). The trim elements (36, 38) are largely insensitive to acceleration about the rotational axis (34), but are sensitive to asymmetrical bending of the substrate (28). Trim signals (72, 74) are received via the trim elements (36, 38) and sense signals (68, 70) are received via sense elements (50, 52). The trim signals (72, 74) are applied to the sense signals (68, 70) to trim an offset error in an output signal of the inertial sensor (20) to produce a compensated sense signal (144).

Abstract: A MEMS resonator system comprises a MEMS resonator, kick start circuitry, feedback circuitry, an oscillator, and a switch. The MEMS resonator system is configured to provide a pulsed kick-start signal having a frequency and period such that energy delivered to the MEMS resonator is optimized in a short period of time, resulting is reduced oscillator startup time. The MEMS resonator system is configured to switch out the kick-start signal when the MEMS resonator oscillation has been achieved, and switch in feedback circuitry to maintain the MEMS resonator in a state of oscillation.

Abstract: Systems and methods are provided for monitoring operation of MEMS gyroscopes (110). A test signal generator (124) is configured to generate and apply a test signal to the rate feedback loop (112) of a MEMS gyroscope (110). A test signal detector (126) is coupled to the quadrature feedback loop (114) of the MEMS gyroscope (110) and is configured to receive a quadrature output signal from the quadrature feedback loop (114). The test signal detector (126) demodulates the quadrature output signal to detect effects of the test signal. Finally, the test signal detector (126) is configured to generate a monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal in the quadrature output signal. Thus, the system is able to provide for the continuous monitoring of the operation of the MEMS gyroscope (110).

Abstract: Systems and methods are provided for improved multifunction sensing. In these embodiments a multifunction sensing device (100) includes a microelectromechanical (MEMS) gyroscope (110) and at least a second sensor (112). The MEMS gyroscope (110) is configured to generate a first clock signal, and the second sensor includes a second clock signal. The multifunction sensing device further includes a reset mechanism (114), the reset mechanism (114) configured to generate a reset signal to set the relative periodic phase alignment of the second clock signal to the first clock signal. Consistently setting the relative periodic phase alignment of the clocks for the other sensor devices (112) to the clock of the MEMS gyroscope (110) can improve the performance of the devices by reducing the probability that varying output offsets will occur in the multiple sensing devices.

Abstract: A multi-mass resonator and a common-mode detection circuit are provided. The common-mode detection circuit, for example, may include a plurality of sensing electrodes, an interface circuit configured to interface with the plurality of sensing electrodes, and a common-mode capacitance extractor circuit electrically coupled in parallel to the interface circuit and configured to detect common-mode capacitance between the plurality of sensing electrodes and output a voltage representative the detected common-mode capacitance, and a differential-mode capacitance extractor circuit electrically coupled in parallel to the interface circuit and configured to detect differential-mode capacitance between the plurality of sensing electrodes and output a voltage representative the detected differential-mode capacitance.

Abstract: A MEMS resonator system comprises a MEMS resonator, kick start circuitry, feedback circuitry, an oscillator, and a switch. The MEMS resonator system is configured to provide a pulsed kick-start signal having a frequency and period such that energy delivered to the MEMS resonator is optimized in a short period of time, resulting is reduced oscillator startup time. The MEMS resonator system is configured to switch out the kick-start signal when the MEMS resonator oscillation has been achieved, and switch in feedback circuitry to maintain the MEMS resonator in a state of oscillation.

Abstract: Systems and methods are provided for monitoring operation of MEMS gyroscopes (110). A test signal generator (124) is configured to generate and apply a test signal to the rate feedback loop (112) of a MEMS gyroscope (110). A test signal detector (126) is coupled to the quadrature feedback loop (114) of the MEMS gyroscope (110) and is configured to receive a quadrature output signal from the quadrature feedback loop (114). The test signal detector (126) demodulates the quadrature output signal to detect effects of the test signal. Finally, the test signal detector (126) is configured to generate a monitor output indicative of the operation of the sensing device based at least in part on the detected effects of the test signal in the quadrature output signal. Thus, the system is able to provide for the continuous monitoring of the operation of the MEMS gyroscope (110).

Abstract: Systems and methods are provided for improved multifunction sensing. In these embodiments a multifunction sensing device (100) includes a microelectromechanical (MEMS) gyroscope (110) and at least a second sensor (112). The MEMS gyroscope (110) is configured to generate a first clock signal, and the second sensor includes a second clock signal. The multifunction sensing device further includes a reset mechanism (114), the reset mechanism (114) configured to generate a reset signal to set the relative periodic phase alignment of the second clock signal to the first clock signal. Consistently setting the relative periodic phase alignment of the clocks for the other sensor devices (112) to the clock of the MEMS gyroscope (110) can improve the performance of the devices by reducing the probability that varying output offsets will occur in the multiple sensing devices.

Abstract: Systems and methods are provided for monitoring operation of MEMS accelerometers (100). In these embodiments a control loop (112) having a forward path (114) is coupled a MEMS transducer (110), and a test signal generator (124) and test signal detector (126) is provided. The test signal generator (124) is configured to generate a test signal and apply the test signal to the forward path (114) of the control loop (112) during operation of the MEMS accelerometer transducer (110). The test signal detector (126) is configured to receive an output signal from the control loop and detect the effects of the test signal in the output signal. Finally, the test signal detector (126) is further configured to generate a monitor output indicative of the operation of the sensing device to provide for the continuous monitoring of the operation of the MEMS accelerometer (100).

Abstract: A semiconductor die (20) includes a substrate (30) and microelectronic devices (22, 26) located at a surface (32) of the substrate (30). A cap (34) is coupled to the substrate (30), and the microelectronic device (22) is positioned in the cavity (24). An outgassing material structure (36) is located within a cavity (24) between the cap (34) and the substrate (30). The outgassing material structure (36) releases trapped gas (37) to increase the pressure within the cavity (24) from an initial pressure level (96) to a second pressure level (94). The cap (34) may include another cavity (28) containing another microelectronic device (26). A getter material (42) may be located within the cavity (28). The getter material (42) is activated to absorb residual gas (46) in the cavity (28) and decrease the pressure within the cavity (28) from the initial pressure level (96) to a third pressure level (92).

Abstract: A micro-electromechanical systems (MEMS) transducer (100, 700) is adapted to use lateral axis vibration to generate non-planar oscillations in a pair of teeter-totter sense mass structures (120/140, 720/730) in response to rotational movement of the transducer about the rotation axis (170, 770) with sense electrodes connected to add pickups (e.g., 102/107, 802/807) diagonally from the pair of sense mass structures to cancel out signals associated with rotation vibration.

Abstract: An inertial sensor has a transducer with a sense resonator. The sense resonator is oscillated. A signal responsive to the oscillation is provided. A first baseband signal and a second baseband signal are provided responsive to the signal responsive to the oscillation of the sense resonator. A signal for controlling a resonance frequency of the sense resonator is provided responsive to performing a Goertzel algorithm on the first baseband signal and the second baseband signal. One use of controlling the resonance frequency is to control an offset between the resonance frequency of the sense resonator and the frequency of the oscillation of drive masses in the sense resonator. Using the Goertzel algorithm is particularly efficient in controlling the resonance frequency.