| CPC G01L 25/00 (2013.01) [G01L 1/142 (2013.01); G01R 31/52 (2020.01); H03F 3/183 (2013.01); H03F 2200/03 (2013.01); H04R 19/04 (2013.01); H04R 2201/003 (2013.01)] | 30 Claims |
|
1. A capacitive sensor, comprising:
a first conductive structure;
a second conductive structure that is different from the first conductive structure, wherein at the second conductive structure is movable relative to the first conductive structure in response to an external force acting thereon, wherein the second conductive structure is capacitively coupled to the first conductive structure to form a first capacitor having a first capacitance that changes with a change in a distance between the first conductive structure and second conductive structure, wherein the first capacitance is representative of the external force and the first capacitor comprises a first micro-electromechanical system (MEMS) output configured to output a first sense signal representative of the first capacitance;
a second capacitor comprising a first terminal and a second terminal, the first terminal being coupled to the first MEMS output of the first capacitor in order to receive the first sense signal and the second terminal being configured to output a second sense signal based on the first sense signal;
an amplifier comprising a first amplifier input coupled to the second terminal of the second capacitor and configured to output a first amplified signal based on the second sense signal; and
a diagnostic circuit configured to receive one of the first sense signal, the second sense signal, or the first amplified signal as a first measurement signal, receive one of the first sense signal, the second sense signal, or the first amplified signal as a second measurement signal that is different from the first measurement signal, generate a first offset measurement based on the first measurement signal and the second measurement signal, wherein the first offset measurement is representative of a degree of pattern similarity between the first measurement signal and the second measurement signal, compare the first offset measurement to a first threshold range defined by a first threshold and a second threshold, and detect a first fault on a condition that the first offset measurement is outside of the first threshold range,
wherein the diagnostic circuit comprises:
a comparator circuit configured to compare the first offset measurement to the first threshold range and activate a first fault signal on the condition that the first offset measurement is outside of the first threshold range; and
an error processing circuit configured to receive the first fault signal and generate a second fault signal in response to the first fault signal being activated, uninterrupted, for a predetermined time interval, wherein the second fault signal is indicative of a confirmation of the first fault.
|