Method and circuit for detecting displacements using microelectromechanical sensors with compensation of parasitic capacitances

摘要

A method for detecting displacements of a micro-electromechanical sensor (101) including a fixed body (3) and a mobile mass (4), forming at least a first sensing capacitor (107) and a second sensing capacitor (108), which are connected to a first input terminal (102) and, respectively, to a first output terminal (104) and to a second output terminal (105) of the sensing circuit and have a rest common sensing capacitance (Cs). The method includes the steps of: closing a first negative-feedback loop (136), which comprises the first sensing capacitor (107) and the second sensing capacitor (108) and a differential amplifier (124); supplying to at least one input (124b) of the differential amplifier (124) a staircase sensing voltage (Vs) through driving capacitors (121, 122) so as to produce variations ( DELTA Vc) of an electrical driving quantity (Vc) which are inversely proportional to the common sensing capacitance (Cs); and driving the sensor (101) with the electrical driving quantity (Vc) .