Microelectromechanical mirror device with piezoelectric actuation and piezoresistive sensing having self-calibration properties

A microelectromechanical mirror device, comprising a die of semiconductor material including:

• a fixed structure defining a cavity;
• a tiltable structure carrying a reflecting region and elastically suspended above the cavity with a main extension in a horizontal plane;
• at least one first pair of driving arms coupled to the tiltable structure and carrying respective piezoelectric material regions that are configured to be biased to cause a rotation of the tiltable structure around a rotation axis that is parallel to a first horizontal axis of said horizontal plane;
• elastic suspension elements configured to elastically couple said tiltable structure to said fixed structure at said rotation axis, wherein the elastic suspension elements are stiff with respect to movement out of the horizontal plane and yielding with respect to torsion around said rotation axis;
• a piezoresistive sensor configured to provide a detection signal indicative of the rotation of the tiltable structure around the rotation axis;
• and
• at least one test structure integrated in said die and configured to provide a calibration signal indicative of a sensitivity variation of the piezoresistive sensor for calibration of said detection signal;
• wherein the sensitivity variation of the piezoresistive sensor is due to geometry variations in manufacturing of said microelectromechanical mirror device;
• wherein said at least one test structure comprises a movable mass operable in resonance by piezoelectric actuation, a resonance frequency associated with said at least one test structure having a variation which is a function of said geometry variations and correlated to said sensitivity variation of the piezoresistive sensor;
• and
• wherein said calibration signal is indicative of the variation of said resonance frequency.