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US 11,692,853 B2Granted
Ultra low power source follower for capacitive sensor shield drivers
AssigneeDisruptive Technologies Research AS
InventorsBjørnar Hernes, Pål Øyvind Reichelt
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Abstract
A source follower for a capacitive sensor device having a sense node and a shield node is provided. The source follower may include a transistor, and a switch array selectively coupling the transistor between the sense node and the shield node. The switch array may be configured to substantially disable current to the transistor during a first mode of operation, precharge the transistor during a second mode of operation, and enable the transistor to copy a sense node voltage to a shield node voltage during a third mode of operation.
Claims20
A method comprising:
- providing a source follower coupled between a sense node of a capacitive sensor device and a shield node of the capacitive sensor device via a switch array of the source follower,
- wherein the source follower includes a transistor and a switch array,
- wherein the switch array selectively couples the transistor between the sense node and the shield node,
- wherein the switch array selectively couples a gate of the transistor between one or more of a supply voltage of the capacitive sensor device, a source follower current of the capacitive sensor device, and an input capacitance of the capacitive sensor device,
- wherein the switch array selectively couples a drain of the transistor between the supply voltage and the source follower current, and
- wherein the switch array selectively couples a source of the transistor between ground of the capacitive sensor device and the shield node to copy a sense node voltage of the sense node to the shield node;
- enabling the switch array in a manner configured to define a first mode of operation, a second mode of operation, and a third mode of operation;
- disabling current to the transistor during the first mode of operation,
- wherein, during the first mode of operation, the gate is shorted to the supply voltage and the sense node and the shield node is shorted to the ground;
- precharging the transistor during the second mode of operation,
- wherein, during the second mode of operation, the gate is coupled to the source follower current;
- and
- enabling the transistor to cause the sense node voltage of the sense node to be substantially equal to a shield node voltage of the shield node during a third mode of operation.
10 more elements
A capacitive sensor device comprising:
- a sense node;
- a shield node;
- and
- a source follower coupled between the sense node and the shield node,
- wherein the source follower includes a transistor and a switch array,
- wherein the switch array selectively couples the transistor between the sense node and the shield node,
- wherein the switch array selectively couples a gate of the transistor between one or more of a supply voltage of the capacitive sensor device, a source follower current of the capacitive sensor device, and an input capacitance of the capacitive sensor device,
- wherein the switch array selectively couples a drain of the transistor between the supply voltage and the source follower current,
- wherein the switch array selectively couples a source of the transistor between ground of the capacitive sensor device and the shield node to copy a sense node voltage of the sense node to the shield node,
- wherein, during a first mode of operation, the gate is shorted to the supply voltage and the sense node and the shield node is shorted to the ground,
- wherein, during a second mode of operation, the gate is coupled to the source follower current, and
- wherein, during a third mode of operation, the sense node voltage of the sense node is substantially equal to a shield node voltage of the shield node.
9 more elements
A source follower comprising:
- a transistor;
- and
- a switch array,
- wherein the source follower is coupled between a sense node of a capacitive sensor device and a shield node of the capacitive sensor device,
- wherein the switch array selectively couples the transistor between the sense node and the shield node,
- wherein the switch array selectively couples a gate of the transistor between one or more of a supply voltage of the capacitive sensor device, a source follower current of the capacitive sensor device, and an input capacitance of the capacitive sensor device,
- wherein the switch array selectively couples a drain of the transistor between the supply voltage and the source follower current,
- wherein the switch array selectively couples a source of the transistor between ground of the capacitive sensor device and the shield node to copy a sense node voltage of the sense node to the shield node,
- wherein, during a first mode of operation, the gate is shorted to the supply voltage and the sense node and the shield node is shorted to the ground,
- wherein, during a second mode of operation, the gate is coupled to the source follower current, and
- wherein, during a third mode of operation, the sense node voltage of the sense node is substantially equal to a shield node voltage of the shield node.
8 more elements
Dependencies are inferred from the claim text.