Patent ID: 11927645
Assignee: INFINEON TECHNOLOGIES AG
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 19:
20. A capacitive sensor, comprising:
a first electrode structure;
a second electrode structure that is counter to the first electrode structure, wherein the second electrode structure is movable relative to the first electrode structure, wherein the second electrode structure is capacitively coupled to the first electrode structure to form a first capacitor having a first capacitance that changes with a change in a distance between the first electrode structure and second electrode structure;
a third electrode structure that is counter to the first electrode structure, wherein the third electrode structure is movable relative to the first electrode structure, wherein the third electrode structure is capacitively coupled to the first electrode structure to form a second capacitor having a second capacitance that changes with a change in a distance between the first electrode structure and third electrode structure,
wherein a pull-in event occurs when the first electrode structure is in direct contact with the second electrode structure causing the first capacitance to be equal to or greater than a pull-in capacitance or when the third electrode structure is in direct contact with the second electrode structure causing the second capacitance to be equal to or greater than the pull-in capacitance,
wherein a non-pull-in event occurs when the first electrode structure is not in direct contact with the second electrode structure causing the first capacitance to be less than the pull-in capacitance and when the third electrode structure is not in direct contact with the second electrode structure causing the second capacitance to be less than the pull-in capacitance;
a differential amplifier configured to receive a first output signal from the first capacitor and a second output signal from the second capacitor, and generate a differential signal based on a difference between the first output signal and the second output signal;
a signal generator configured to apply an AC signal at an input or at an output of the first capacitor and at an input or at an output of the second capacitor to induce a first output response at the output of the first capacitor and to induce a second output response at the output of the second capacitor, respectively; and
a diagnostic circuit configured to detect a fault in the capacitive sensor by evaluating the differential signal and detecting the fault based on the differential signal and based on whether the AC signal is a pull-in signal or a non-pull-in signal.