Stmicroelectronics S.r.l.

Emanuele Lavelli

Andrea Donadel

Stefano Polesel

A driving circuit for controlling a MEMS oscillator includes a digital conversion stage to acquire a differential sensing signal indicative of a displacement of a movable mass of the MEMS oscillator, and to convert the differential sensing signal of analog type into a digital differential signal of digital type. Processing circuitry is configured to generate a digital control signal of digital type as a function of the comparison between the digital differential signal and a differential reference signal indicative of a target amplitude of oscillation of the movable mass which causes the resonance of the MEMS oscillator. An analog conversion stage includes a ΣΔ DAC and is configured to convert the digital control signal into a PDM control signal of analog type. A filtering stage of low-pass type, by filtering the PDM control signal, generates a control signal for controlling the amplitude of oscillation of the movable mass.

Driving circuit for controlling a MEMS oscillator of resonant type

A microelectromechanical gyroscope includes a support structure, a driving mass movable according to a driving axis; and an oscillating microelectromechanical loop. The microelectromechanical loop has a resonance frequency and a loop gain and includes the driving mass, a sensing interface that senses a position of the driving mass, and a gain control stage that maintains a modulus of the loop gain at a unitary value at the resonance frequency. The gain control stage includes a sampler and an transconductance operational amplifier in an open-loop configuration. The sampler acquires samples of a loop signal from the sensing interface in a first operative condition and transfers them to the transconductance operational amplifier in a second operative condition. The sampler decouples the transconductance operational amplifier from the sensing interface in the first operative condition and in the second operative condition.

Microelectromechanical gyroscope having a resonant driving loop with controlled oscillation amplitude and method of controlling a microelectromechanical gyroscope

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Mandello del Lario, Italy

Emanuele Lavelli