Nxp Usa, Inc.

Freescale Semiconductor,inc.

Keith L Kraver

Mark Edward Schlarmann

Deyou Fang

Chad S Dawson

Gerhard Trauth

Sung Jin Jo

Shiraz Contractor

Heinz Loreck

Mike A Margules

Yizhen Lin

Dejan Mijuskovic

David A Hayner

Todd Frederick Miller

Gary G Li

Pascal Kamel Abouda

Margaret Leslie Kniffin

Marianne Maleyran

Marco Fuhrmann

Raghavendra N Sridhar

Hiroto Sahara

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.

Trim circuit and method of oscillator drive circuit phase calibration

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.

Sensor interface circuit, sensor system, and method of signal measurement

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.

System and method for continuous monitoring of a gyroscope

Systems and methods for converting a capacitance signal into a band-limited voltage signal for improved signal processing are disclosed herein. Such systems can include a capacitance-to-voltage converter configured to convert a capacitive signal from a capacitive device that operates at a mechanical frequency into a raw voltage signal, a clock generator configured to convert the mechanical frequency into one or more clock signals, and a filter component configured to apply a band-pass filter response to the raw voltage signal to convert the raw voltage signal into a band-limited voltage signal. The clock generator can be configured to apply the one or more clock signals to the filter component to drive a first pole and a second pole of the band-pass filter response to track the mechanical frequency of the capacitive device such that the geometric mean of the first pole and the second pole is substantially equal to the mechanical frequency.

Capacitance-to-voltage interface circuit

Devices, systems and methods are provided for calibrating a transducer. One exemplary method involves determining a transfer function for the transducer based on a measured response of the transducer to an applied electrical signal, determining a set of values for a plurality of response parameters associated with the transducer based on the transfer function, determining a calibration coefficient value associated with the transducer based at least in part on the set of values and a correlation between physical sensitivity and the plurality of response parameters, and storing the calibration coefficient value in association with the transducer.

Methods and systems for electrically calibrating transducers

A pressure sensor device and a method for testing the pressure sensor device is provided. The pressure sensor device includes a first pressure sensor cell having a first capacitance value, and a second pressure sensor cell having a second capacitance value, the second capacitance value being different from the first capacitance value. In one embodiment, the method includes determining a temperature coefficient offset to test for faults in the pressure sensor device. In another embodiment, the method includes determining a differential mode calculation and a common mode calculation. A fault exists if the differential and common mode calculations do not agree.

Pressure sensor device and method for testing the pressure sensor device

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. A signal processing unit, coupled with the C/V converter, extracts a sense signal from the differential-mode output signal, extracts a diagnostic signal from said common-mode out signal, and detects a fault condition in the sensor system when a difference between the sense and diagnostic signals is outside a preset limit.

Sensor device and method for continuous fault monitoring of sensor device

A micro-electromechanical systems (MEMS) transducer () is adapted to use lateral axis vibration to generate non-planar oscillations in a pair of teeter-totter sense mass structures () in response to rotational movement of the transducer about the rotation axis () with sense electrodes connected to add pickups (e.g.,) diagonally from the pair of sense mass structures to cancel out signals associated with rotation vibration.

Vibration robust x-axis ring gyro transducer

Systems and methods are provided for monitoring operation of MEMS accelerometers (). In these embodiments a control loop () having a forward path () is coupled a MEMS transducer (), and a test signal generator () and test signal detector () is provided. The test signal generator () is configured to generate a test signal and apply the test signal to the forward path () of the control loop () during operation of the MEMS accelerometer transducer (). The test signal detector () 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 () 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 ().

System and method for monitoring an accelerometer

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.

Electro-mechanical oscillator and common-mode detection circuit

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.

System and method for improved MEMS oscillator startup

Systems and methods are provided for monitoring operation of MEMS gyroscopes (). A test signal generator () is configured to generate and apply a test signal to the rate feedback loop () of a MEMS gyroscope (). A test signal detector () is coupled to the quadrature feedback loop () of the MEMS gyroscope () and is configured to receive a quadrature output signal from the quadrature feedback loop (). The test signal detector () demodulates the quadrature output signal to detect effects of the test signal. Finally, the test signal detector () 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 ().

System and method for monitoring a gyroscope

Systems and methods are provided for improved multifunction sensing. In these embodiments a multifunction sensing device () includes a microelectromechanical (MEMS) gyroscope () and at least a second sensor (). The MEMS gyroscope () 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 (), the reset mechanism () 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 () to the clock of the MEMS gyroscope () can improve the performance of the devices by reducing the probability that varying output offsets will occur in the multiple sensing devices.

System and method for reducing offset variation in multifunction sensor devices

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.

MEMS inertial sensor with frequency control and method

An apparatus () and method () for sensing acceleration are provided. The method includes producing () a first signal in response to an acceleration sensed by a transducer, producing () a second signal based on the first signal, and actuating () the transducer in response to the second signal to remove offset in the transducer. The first signal represents the acceleration, and the second signal represents a low frequency component associated with an offset in the transducer. The apparatus () includes a transducer () producing a capacitance in response to the acceleration, a sensing system () producing a first signal from the capacitance representing the acceleration, and a compensation system () coupled between the sensing system and transducer. The compensation system produces a second signal based on the first signal for substantially removing an offset of the transducer.

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Gilbert, AZ, United States of America

Keith L Kraver