Patent ID: 9696375
Date: 2017-07-04
CPC Classifications: G01P,G01R

Claim:
1. A capacitive sensor, comprising: at least one capacitive element; a switched-capacitor readout circuit configured to detect at least one signal capacitance that results from motions of the at least one capacitive element; a first switch arrangement configured to electrically couple the switched-capacitor readout circuit part to the at least one capacitive element for a front end readout period, and to electrically decouple the switched-capacitor readout circuit part from the at least one capacitive element for a front end reset period; a self-test controller configured to enable and disable a self-test of the capacitive sensor; an actuation circuit configured to generate a self-test bias voltage for electrostatic deflection of the at least one capacitive element; a second switch arrangement configured to electrically couple the self-test bias voltage of the actuation circuit part to the at least one capacitive element during a first period, wherein the first period is synchronized to the front end reset period and is configured to occur when the self-test of the capacitive sensor is enabled by the self-test controller, and to electrically decouple the actuation circuit part from the at least one capacitive element in times other than the first period, wherein the actuation circuit includes a high-voltage charge pump and a high-voltage charge pump control circuitry configured to enable and disable generation of the self-test bias voltage by the high-voltage charge pump, wherein the second switch arrangement is configured to generate a self-test control signal, a first state of the self-test control signal relating to the first period, and the second state of the self-test control signal relating to the times other than the first period, and wherein the high-voltage charge pump control circuitry is responsive to the self-test control signal such that enabling and disabling generation of the self-test bias voltage by the high-voltage charge pump depends on the self-test control signal.