Stmicroelectronics Gmbh

Stmicroelectronics S.r.l.

Naren K Sahoo

Yamu Hu

David C McClure

Deyou Fang

Huantong Zhang

Anthony Junior Casillan

Alessandro Gasparini

Alessandro Tocchio

Tom Youssef

Pavan Nallamothu

Marco Garbarino

At start-up of a microelectromechanical system (MEMS) gyroscope, the drive signal is inhibited, and the phase, frequency and amplitude of any residual mechanical oscillation is sensed and processed to determine a process path for start-up. In the event that the sensed frequency of the residual mechanical oscillation is a spurious mode frequency and a quality factor of the residual mechanical oscillation is sufficient, an anti-phase signal is applied as the MEMS gyroscope drive signal in order to implement an active dampening of the residual mechanical oscillation. A kicking phase can then be performed to initiate oscillation. Also, in the event that the sensed frequency of the residual mechanical oscillation is a resonant mode frequency with sufficient drive energy, a quadrature phase signal with phase lock loop frequency control and amplitude controlled by the drive energy is applied as the MEMS gyroscope drive signal in order to induce controlled oscillation.

MEMS gyroscope start-up process and circuit

A microelectromechanical system (MEMS) gyroscope sensor has a sensing mass and a quadrature error compensation control loop for applying a force to the sensing mass to cancel quadrature error. To detect fault, the quadrature error compensation control loop is opened and an additional force is applied to produce a physical displacement of the sensing mass. A quadrature error resulting from the physical displacement of the sensing mass in response to the applied additional force is sensed. The sensed quadrature error is compared to an expected value corresponding to the applied additional force and a fault alert is generated if the comparison is not satisfied.

MEMS gyroscope self-test using a technique for deflection of the sensing mobile mass

A microelectromechanical system (MEMS) accelerometer sensor has a mobile mass and a sensing capacitor. To self-test the sensor, a test signal is applied to the sensing capacitor during a reset phase of a sensing circuit coupled to the sensing capacitor. The test signal is configured to cause an electrostatic force which produces a physical displacement of the mobile mass corresponding to a desired acceleration value. Then, during a read phase of the sensing circuit, a variation in capacitance of sensing capacitor due to the physical displacement of the mobile mass is sensed. This sensed variation in capacitance is converted to a sensed acceleration value. A comparison of the sensed acceleration value to the desired acceleration value provides an indication of an error in operation of the MEMS accelerometer sensor if the sensed acceleration value and desired acceleration value are not substantially equal.

MEMS accelerometer self-test using an active mobile mass deflection technique

A modulated digital input signal is passed through a conditioning circuit to generate a first input signal. An error amplifier circuit receives the first input signal and a second input signal, and controls the operation of a MOS transistor to generate an output signal that is current modulated. The output signal is sensed to generate a feedback signal. A switching circuit selectively applies the feedback signal as the second input signal in response to a transition of the modulated digital input signal from a first logic state to a second logic state. The switching circuit alternatively selectively applies a fixed reference signal as the second input signal to the error amplifier in response to a transition of the modulated digital input signal from the second logic state to the first logic state.

Current modulation circuit

A self test for a counter system in an integrated circuit includes a clock coupled to counters in a plurality of counters. A first counter in the plurality of counters has a first counter output and a first counter rollover. A second counter in the plurality of counters has a second counter output, a second counter rollover less than the first counter rollover, and a second counter rollover signal that is active when the second counter has rolled over. A comparison circuit having inputs coupled to the first and second counter outputs, compares the first and second counter outputs to produce a counter error output signal. A latch latches the counter error output signal in response to the second counter rollover signal being inactive and the counter error output signal indicating a difference in the first and second counter outputs. Counters may be segmented to reduce a number of digits.

Built-in self test for a counter system

A sense amplifier circuit for a memory cell includes a sense amplifier that is operable to be coupled to a memory cell via data lines, and including read bus complement and read bus true lines operative with a data output through which a data output signal is passed. An equalization circuit and enable circuit are operable with the sense amplifier. A control circuit is operable for disconnecting the data output from preferably the one of the read bus complement line and minimize unwanted transitions on the data output signal.

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Frisco, TX, United States of America

Naren K Sahoo