Patent ID: 8629684

Claim:
An electronic circuit comprising: (a) a capacitive sensor disposed to measure a physical parameter, wherein the sensor includes at least two differential-mounted capacitors, wherein each differential-mounted capacitor has a fixed electrode, wherein the at least two differential-mounted capacitors share a common electrode that is movable relative to each fixed electrode of the at least two capacitors, and wherein the common electrode is moved to alter the capacitive value of each capacitor during measurement of the physical parameter; and (b) an interface connected to the capacitive sensor, wherein the interface includes (i) a charge transfer amplifier unit connected to the common electrode, (ii) an integrator unit disposed to integrate the charges supplied by the charge transfer amplifier unit and to supply an output voltage, wherein the integrator unit includes a first compensation capacitor at input, (iii) an excitation unit arranged between the output of the integrator unit and the sensor, wherein the excitation unit is disposed to polarize each fixed electrode of the sensor capacitors at a determined voltage value, and (iv) comparison means disposed to compare the output voltage with a comparison voltage and to control disconnection of the compensation capacitor at the integrator unit input if the deviation between the output voltage and the comparison voltage is above a determined voltage threshold; wherein the comparison means is a dynamic comparator, wherein the comparison means includes at input a threshold capacitor that is connected to a control capacitor and disposed to define a capacitive ration, and wherein the capacitive ratio determines, by multiplying by a voltage value that corresponds to a low potential subtracted from a high potential of the supply voltage source, the determined voltage threshold; wherein a first electrode of the threshold capacitor is connected at input via a first switch of the comparator to the high potential and via a second switch to the low potential of the supply voltage source, wherein a second electrode of the threshold capacitor is connected to a second electrode of the control capacitor and defines a connection node, wherein the first electrode of the control capacitor is connected, via a third switch, to the comparison voltage and, via a fourth switch, to the output voltage of the first integrator unit; and wherein the switches are controlled by the dynamic comparator, and wherein the comparator compares the output voltage subtracted from the comparison voltage, and the comparison voltage subtracted from the output voltage.