Analog to digital converter with adjustable conversion window
First Claim
1. An apparatus comprising:
- a first capacitor system having a first variable capacitance, the first variable capacitance based, at least in part, upon a number of engaged capacitors of a first plurality of selectively engagable capacitors, the first capacitor system selectively coupled to a first reference voltage;
a second capacitor system having a second variable capacitance, the second variable capacitance based, at least in part, upon a number of engaged capacitors of a second plurality of selectively engagable capacitors, the second capacitor system selectively coupled to a second reference voltage;
a switch coupled to the first capacitor system and the second capacitor system, the switch configured to transfer charge between the first capacitor system and the second capacitor system when the switch is closed such that the first capacitor system and the second capacitor system each store the same first voltage, the first voltage less than the first reference voltage; and
a node coupled to the first capacitor system, the second capacitor system, and a first input of a differential amplifier of an analog to digital converter, the node configured to bias the differential amplifier to the first voltage.
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Abstract
In one embodiment, an apparatus includes a first capacitor system and a second capacitor system. Each capacitor system comprises one or more engaged capacitors from respective pluralities of selectively engagable capacitors. The first capacitor system and second capacitor system are respectively selectively coupled to a first reference voltage and a second reference voltage. The apparatus further includes a switch configured to transfer charge between the first capacitor system and the second capacitor system when the switch is closed such that the first capacitor system and the second capacitor system each store the same first voltage. The apparatus further includes a node coupled to the first capacitor system, the second capacitor system, and a first input of a differential amplifier of an analog to digital converter. The node is configured to bias the differential amplifier to the first voltage.
18 Citations
21 Claims
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1. An apparatus comprising:
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a first capacitor system having a first variable capacitance, the first variable capacitance based, at least in part, upon a number of engaged capacitors of a first plurality of selectively engagable capacitors, the first capacitor system selectively coupled to a first reference voltage; a second capacitor system having a second variable capacitance, the second variable capacitance based, at least in part, upon a number of engaged capacitors of a second plurality of selectively engagable capacitors, the second capacitor system selectively coupled to a second reference voltage; a switch coupled to the first capacitor system and the second capacitor system, the switch configured to transfer charge between the first capacitor system and the second capacitor system when the switch is closed such that the first capacitor system and the second capacitor system each store the same first voltage, the first voltage less than the first reference voltage; and a node coupled to the first capacitor system, the second capacitor system, and a first input of a differential amplifier of an analog to digital converter, the node configured to bias the differential amplifier to the first voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method comprising:
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engaging a number of capacitors of a first capacitor system comprising a first plurality of selectively engagable capacitors; engaging a number of capacitors of a second capacitor system comprising a second plurality of selectively engagable capacitors; coupling the first capacitor system to a first reference voltage; coupling the second capacitor system to a second reference voltage; transferring charge between the first capacitor system and the second capacitor system such that the first capacitor system and the second capacitor system each stores the same first voltage, the first voltage less than the first reference voltage; and biasing a differential amplifier of an analog to digital converter to the first voltage by a node coupled to the first capacitor system, the second capacitor system, and the differential amplifier. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. An apparatus, comprising:
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a capacitive touch sensor comprising a plurality of nodes; and a control unit coupled to the capacitive touch sensor, the control unit comprising; a first capacitor system having a first variable capacitance, the first variable capacitance based, at least in part, upon a number of engaged capacitors of a first plurality of selectively engagable capacitors, the first capacitor system selectively coupled to a first reference voltage; a second capacitor system having a second variable capacitance, the second variable capacitance based, at least in part, upon a number of engaged capacitors of a second plurality of selectively engagable capacitors, the second capacitor system selectively coupled to a second reference voltage; a switch coupled to the first capacitor system and the second capacitor system, the switch configured to transfer charge between the first capacitor system and the second capacitor system when the switch is closed such that the first capacitor system and the second capacitor system each store the same first voltage, the first voltage less than the first reference voltage; and a node coupled to the first capacitor system, the second capacitor system, and a first input of a differential amplifier of an analog to digital converter, the node configured to bias the differential amplifier to the first voltage. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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Specification