Capacitive microelectromechanical sensor with self-test capability
First Claim
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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, andwherein 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.
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Abstract
A capacitive sensor that includes at least one capacitive element and a switched-capacitor readout circuit part for detecting at least one signal capacitance that results from motions of the capacitive element. The self-test bias voltage of the actuation circuit part is coupled to the capacitive element during a first period that is synchronized to the front end reset period and occurs when the self-test of the capacitive sensor is enabled by the self-test controller.
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Citations
20 Claims
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1. A capacitive sensor, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A self-test method for a capacitive sensor that includes at least one capacitive element, a switched-capacitor readout circuit part for detecting at least one signal capacitance that results from motions of the at least one capacitive element, and 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, the method comprising:
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generating in the capacitive sensor a self-test bias voltage for electrostatic deflection of 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; electrically decoupling the self-test bias voltage from the at least one capacitive element in times other than the first period; generating a self-test control signal, wherein a first state of the self-test control signal relates to the first period, and the second state of the self-test control signal relates to the times other than the first period; and enabling and disabling generation of the self-test bias voltage by the high-voltage charge pump in response to the self-test control signal. - View Dependent Claims (19, 20)
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Specification