Circuits and methods for sensing resistance
AssigneeQUALCOMM Incorporated
InventorKenneth C. Adkins
Life of this patent
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Abstract
Embodiments of the present invention include circuits and methods for sensing resistance. In one embodiment, a current is generated into a node. The node is coupled to a first terminal of a resistor. A second terminal of the resistor is coupled in series with a capacitance and a reference voltage. The current is turned off when a voltage on the node meets a threshold. A second voltage is detected on the node after the current is turned off. A resistance value is determined based on the first voltage on the node and the second voltage on the node. In one embodiment, the resistor is external to an integrated circuit and sensed through a single pin of the integrated circuit. The integrated circuit may include a current source, comparator, and a digital-to-analog converter.
Claims20
A method comprising:
- generating a current into a node, wherein the node is coupled to a first terminal of a resistor, and wherein a second terminal of the resistor is coupled in series with a capacitance and a reference voltage;
- turning off the current when a voltage on the node meets a threshold, the threshold corresponding to the voltage on the node having a first voltage;
- detecting a second voltage on the node after the current is turned off;
- and
- determining a resistance value of said resistor based on said current, the first voltage on the node and the second voltage on the node.
A resistance sensing circuit comprising:
- a current source to generate a current into a node, wherein the node is coupled to a first terminal of a resistor, and wherein a second terminal of the resistor is coupled in series with a capacitance and a reference voltage;
- a threshold detection circuit coupled to the node and to the current source, wherein the threshold detection circuit turns off the current when a voltage on the node meets a threshold, the threshold corresponding to a first voltage on the node;
- and
- a voltage measurement circuit coupled to the node to detect a second voltage on the node after the current is turned off,
- wherein said current and a difference between the first voltage on the node and the second voltage on the node corresponds to a resistance value of said resistor.
Dependencies are inferred from the claim text.