Device for measuring a variation in the capacitance of a variable capacitive structure

A device for measuring a variation (ΔCX) in the capacitance of a variable capacitive structure (CX), comprising:

• a supply voltage (VCC;
• means for charging the variable capacitive structure (CX) using the supply voltage (VCC);
• means for discharging the variable capacitive structure (CX) into a reference capacitance (CS) in a fixed number (x) of discharges;
• means for measuring a voltage (VS) across the terminals of the reference capacitance;
• means for charging a measurement capacitive structure (CM) using the supply voltage (VCC);
• means for discharging the measurement capacitive structure (CM) into the reference capacitance (CS) in a variable number (n) of discharges;
• and
• means for detecting a threshold voltage (VTH) across the terminals of the reference capacitance (CS),
• characterized in that the device is configured/programmed so that the discharge of the measurement capacitive structure (CM), in a variable number (n) of discharges, into the reference capacitance (CS) is carried out after the variable capacitive structure (CX) has been discharged, in the fixed number (x) of discharges, into the reference capacitance (CS), and in that the variation in the variable number (n) of discharges relative to a previously obtained number of discharges allows the variation (ΔCX) in the capacitance of the variable capacitive structure (CX) to be estimated.