Stmicroelectronics S.r.l.

Stefano Polesel

Germano Nicollini

Andrea Donadel

Emanuele Lavelli

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

A current mirror includes first and second transistors having current paths coupled to an input current line. The current paths for the first and second transistors are referenced to ground via respective first and second resistors having resistance values twice a first resistance value. The first transistor is diode connected. A third transistor has a current path coupled to an output current line and referenced to ground via a third resistor having a second resistance value equal to the first resistance value divided by a mirror factor. Control terminals of the first and third transistors are coupled together, and further coupled to a control terminal of the second transistor through a coupling resistor. A first capacitor is coupled between ground and the control terminal of the second transistor unit. A second capacitor is coupled between ground and the current path through the third transistor.

Frequency compensation circuit and corresponding device

A first current proportional to absolute temperature flows in a first current line through a first p-n junction and a second p-n junction arranged in series. A cascaded arrangement of p-n junctions is coupled to the second p-n junction and includes a further p-n junction with a current flowing therethrough that has a third order proportionality on absolute temperature. A differential circuit has a first input coupled to the further p-n junction and a second input coupled to a current mirror from the first p-n junction, with the differential circuit configured to generate a bandgap voltage with a low temperature drift from a sum of first voltage (that is PTAT) derived from the first current and a second voltage (that is PTAT) derived from the third current.

Bandgap reference circuit, corresponding device and method

An amplifier circuit a differential input stage coupled to a first input and to a second input between which a differential input voltage is present. A converter stage is coupled to the input stage to convert the differential input voltage into a converted voltage. An output stage is coupled to the converter stage and generates, starting from the converted voltage, an output voltage on a single output of the amplifier circuit. A biasing stage is coupled to the input stage and to the output stage to supply a biasing current. A chopper module reduces a contribution of offset and noise associated with the output voltage. The chopper module is coupled to the input stage, converter stage, and to the biasing stage. The chopper module includes an input chopper stage, a converter chopper stage, and a biasing chopper stage that operate jointly under control of a chopper signal.

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Treviso, Italy

Stefano Polesel