Stmicroelectronics S.r.l.

Stmicroelectronics Gmbh

Marco Garbarino

Andrea Donadel

Davide Magnoni

Germano Nicollini

Carlo Valzasina

David C McClure

Paolo Angelini

Francesco Rizzini

Roberto Modaffari

Roberto Pio Baorda

Pavan Nallamothu

Yamu Hu

Federico Guanziroli

Deyou Fang

Naren K Sahoo

Davy Choi

Francesco Borgioli

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 current measurement circuit, for wireless charging systems, for instance, comprises a differential input configured to have applied an input voltage sensed across a shunt resistor traversed by a current to be measured, a voltage reversal switch arrangement selectively switchable to reverse the polarity of the input voltage as applied between a first and a second voltage sensing nodes as well as a first and a second current flow line between the voltage sensing nodes and ground. A difference resistor intermediate the two current flow lines is traversed by a current which is a function of the input voltage as applied to the first and second sensing nodes via the voltage reversal switch arrangement. First and second current sensing nodes at the two current flow lines are coupled to a differential current output via a current reversal switch arrangement selectively switchable to reverse the output current polarity.

Sensing circuit, corresponding device and method

A gyroscope includes: a mass, which is movable with respect to a supporting body; a driving loop for keeping the mass in oscillation according to a driving axis; a reading device, which supplying an output signal indicating an angular speed of the body; and a compensation device, for attenuating spurious signal components in quadrature with respect to a velocity of oscillation of the mass. The reading device includes an amplifier, which supplies a transduction signal indicating a position of the mass according to a sensing axis. The compensation device forms a control loop with the amplifier, extracts from the transduction signal an error signal representing quadrature components in the transduction signal, and supplies to the amplifier a compensation signal such as to attenuate the error signal.

Microelectromechanical gyroscope with compensation of quadrature signal components

An electronic circuit for amplifying signals with two components in phase quadrature, which includes: a feedback amplifier with a feedback capacitor; a switch that drives charging and discharging of the feedback capacitor; an additional capacitor; and a coupling circuit, which alternatively connects the additional capacitor in parallel to the feedback capacitor or else decouples the additional capacitor from the feedback capacitor. The switch opens at a first instant, where a first one of the two components assumes a first zero value; the coupling circuit decouples the additional capacitor from the feedback capacitor in a way synchronous with a second instant, where the first component assumes a second zero value.

Amplifying electronic circuit with reduced start-up time for a signal including quadrature components

A phase shifter, which carries out a ninety-degree phase shift of a sinusoidal input signal having an input frequency, at the same input frequency, envisages: a continuous-time all-pass filter stage, which receives the sinusoidal input signal and generates an output signal phase-shifted by 90&#xb0; at a phase-shift frequency that is a function of a RC time constant of the all-pass filter stage; and a calibration stage, which is coupled to the all-pass filter stage and generates a calibration signal for the all-pass filter stage, such that the phase-shift frequency is equal to the input frequency of the sinusoidal input signal, irrespective of variations of the value of the input frequency and/or of the RC time constant with respect to a nominal value.

Ninety-degree phase shifter circuit and corresponding ninety-degree phase-shifting method

An amplifier includes a first input branch and a second input branch that form a differential input stage and a current mirror connected to the differential input. The current mirror is governed as a function of a common mode feedback signal applied to a control node of the current mirror. A second, amplification, stage includes a branch flowing through which is a current, which is a function of the current that flows in the first input branch, and is in turn connected to a first output branch. A capacitive element is coupled between the control node and the second stage. The circuit is symmetrical with respect to the input stage.

Differential amplifier with common mode compensation circuit

A microelectromechanical device includes: a body; a movable mass, elastically coupled to the body and oscillatable with respect to the body according to a degree of freedom; a frequency detector, configured to detect a current oscillation frequency of the movable mass; and a forcing stage, capacitively coupled to the movable mass and configured to provide energy to the movable mass through forcing signals having a forcing frequency equal to the current oscillation frequency detected by the frequency detector, at least in a first transient operating condition.

Microelectromechanical device having an oscillating mass and a forcing stage, and method of controlling a microelectromechanical device

A method and apparatus for compensating current leakage is disclosed. In the method and apparatus, a differential amplifier receives a first input signal and a second input signal and outputs a first output signal and a second output signal. The first output signal is filtered to obtain a first filtered signal. The first filtered signal is compared to the first input signal and a first compensation signal is outputted having a first voltage that is a function of a difference between a voltage of the first filtered signal and a voltage of the first input signal. Current leakage in the first input signal is compensated for using the first compensation signal.

Capacitance to voltage converter with a leakage compensation loop

A driving device of a driving mass of a gyroscope comprises a differential read amplifier to supply first signals indicating a rate of oscillation of the driving mass; a variable-gain amplifier to supply second signals to drive the driving mass based on said first signals; a voltage elevator providing a power supply signal to the variable-gain amplifier; a controller generating a first control signal to control a gain of the variable-gain amplifier; and a first comparator, coupled to the variable-gain amplifier, generating a second control signal based on a comparison of the first control signal with a threshold, the second control signal controlling at least one among: (i) the variable-gain amplifier in such a way that the gain is increased only during the start-up phase of the gyroscope, and (ii) the voltage elevator in such a way that the power supply signal is increased only during the start-up phase.

Microelectromechanical gyroscope with improved start-up phase, system including the microelectromechanical gyroscope, and method for speeding-up the start up phase

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Bareggio, Italy

Marco Garbarino