Patent ID: 7532016

Claim:
An electronic interface circuit for a capacitive sensor for measuring a physical parameter, the sensor including at least two differential mounted capacitors whose a common electrode is able to move relative to each fixed electrode of the two capacitors in order to alter the capacitive value of each capacitor when the physical parameter is measured, said electronic circuit including: (a) a charge transfer amplifier unit connected to the common electrode; (b) a first integrator unit for integrating the charges supplied by the charge transfer amplifier unit; and (c) a first excitation unit arranged between the output of the first integrator unit and the sensor for polarizing each fixed electrode of the capacitors at a determined voltage value, or for discharging each capacitor by an output voltage of the first integrator unit; (d) a second integrator unit for integrating the charges supplied by the charge transfer amplifier, wherein the first and second integrator units are arranged to operate alternately and cyclically each measurement period; and (e) a second excitation unit arranged between the output of the second integrator unit and the sensor for polarizing each fixed electrode of the capacitors at a determined voltage value opposite to the voltage value controlled by the first excitation unit, or for discharging each capacitor by an output voltage of the second integrator unit, wherein the first and second excitation units are arranged to operate alternately and cyclically each measurement period, wherein the first excitation unit operates with the first integrator unit and the second excitation unit operates with the second integrator unit so that the electronic circuit operates entirely symmetrically for the physical parameter measurement.