Device and method for automatic calibration of a microelectromechanical structure included in a control loop

A sensing device, comprising:

• an inertial sensor comprising a stator element and a rotor element electrostatically coupled together;
• a position interface circuit coupled to the inertial sensor and configured to generate a position signal indicative of the position of the rotor element;
• a quantizer coupled to the position interface and configured to receive the position signal and to generate a sequence of samples;
• a main actuator coupled to the output of the quantizer for receiving the sequence of samples and configured to modify a position of the rotor element;
• an adder having an output coupled to the inertial sensor and a first input coupled to the actuator;
• a computation circuit having an input coupled to the output of the quantizer and configured to generate a mean value of the sequence of samples;
• a processing circuit having an input coupled to the computation circuit and configured to receive the mean value of the sequence of samples and to generate a driving signal;
• and
• a secondary actuator having an input coupled to the processing circuit and an output coupled to the adder, the secondary actuator configured to generate a calibration acceleration signal to be applied to the rotor to compensate for voltage offsets and component mismatches.

A sensing device, comprising:

• an inertial sensor comprising a stator element and a rotor element electrostatically coupled together;
• a main feedback branch coupled to the inertial sensor and including a main actuator configured to generate a primary feedback signal for changing the position of the rotor element relative to the stator element;
• and
• a secondary feedback branch coupled to the main feedback branch and to the inertial sensor, the secondary feedback branch comprising a computation circuit configured to receive a sequence of sample signals from the main feedback branch and to generate a mean value signal corresponding to the mean value of the sequence of samples, a processing circuit having an input coupled to the computation circuit and configured to generate a driving signal in response to the mean value signal, and a secondary actuator having an input coupled to the processing circuit and configured to receive the driving signal and to generate a secondary feedback signal that is received by an adder coupled to the input of the inertial sensor.

A method of calibrating an inertial sensor having a stator element and a rotor element electrostatically coupled together and controlled by a main feedback branch having a quantizer that generates a sequence of samples to a main actuator that in turn generates a first feedback signal to the inertial sensor, the calibration method comprising:

• receiving the sequence of samples at a computation circuit and generating therefrom a mean value signal;
• receiving the mean value signal at a processing circuit and generating therefrom a voltage calibration signal;
• receiving the voltage calibration signal at a secondary actuator and generating therefrom a secondary feedback signal;
• and
• adding the secondary feedback signal to the primary feedback signal and combining the same with an input signal and outputting the sum thereof to the inertial sensor.