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US 5,629,698 AGranted
Automatic offset tracking and correcting circuit and method of operation
AssigneeTexas Instruments Incorporated
InventorMichiel De Wit
Life of this patent
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Abstract
An analog-to-digital conversion system (6) is provided which includes an analog-to-digital converter (8) having a first node (NODE 1) and a second node (NODE 2). An automatic offset tracking and correcting circuit (10) is coupled to the first node (NODE 1) and the second node (NODE 2).
Claims20
An analog-to-digital conversion system, comprising:
- a sampling network comprising a plurality of capacitors having a first node of each capacitor coupled to a common node;
- and
- an automatic offset tracking and correcting circuit coupled to the common node of the sampling network and operable to sense an offset voltage present on the common node during the operation of the sampling network and to inject charge onto the common node and pull charge from the common node responsive to the sensing of the offset voltage in order to reduce the offset voltage, wherein the automatic offset tracking and correcting circuit is operable to sense a sign of the offset voltage and to inject and pull charge responsive to the sign of the offset voltage.
An analog-to-digital conversion system, comprising:
- an analog-to-digital converter comprising a comparator output node, a capacitor top plate node and an offset voltage;
- a latch coupled to the comparator output node and operable to sense when the offset voltage is above ground potential and when the offset voltage is below ground potential;
- a counter coupled to the latch and operable to maintain a count by incrementing when the offset voltage is above ground potential and decrementing when the offset voltage is below ground potential;
- a digital-to-analog converter control coupled to the counter and operable to receive the count maintained by the counter and to provide control signals;
- and
- a digital-to-analog converter coupled to the digital-to-analog converter control and operable to provide an output voltage level responsive to the control signals provided by the digital-to-analog converter control.
3 more elements
A method of tracking and correcting an offset voltage in an analog-to-digital conversion system, comprising the steps of:
- sensing an offset voltage present on a node in an analog-to-digital conversion system;
- setting a charge sign and an amount of charge to provide to the node;
- reducing the offset voltage by injecting the amount of charge onto the node when the charge sign is positive and by pulling the amount of charge from the node when the charge sign is negative;
- and
- repeating the steps of sensing, setting and reducing after each conversion and before a next conversion.
2 more elements
Dependencies are inferred from the claim text.