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US 6,275,090 B1Granted
Adaptive resistor trimming circuit
AssigneeAgere Systems Guardian Corp.
InventorsHarley Franklin Burger, Jr., Jeffrey Lee Sonntag, Suharli Tedja
Life of this patent
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AssigneeAgere Systems Guardian Corp.
InventorsHarley Franklin Burger, Jr., Jeffrey Lee Sonntag, Suharli Tedja
Estimating the term…
An integrated circuit includes a self-calibrating resistor circuit comprising a resistor string, a comparator, a state machine, a reference voltage source, and a reference current source. The current source typically comprises a voltage reference, typically a bandgap reference, and a temperature-independent resistor having a value REXT. In operation, a reference current IREF flows through the resistor string. During a calibration period, the voltage across the string is compared to the bandgap reference voltage, VBG, by the comparator, which controls the state of the state machine. The outputs of the state machine turn on or off the resistors in the string until the voltage across the string, VR, is approximately equal to the reference voltage. The resistance of the resistor string is then equal to RBG=VBG/IREF, which is proportional to REXT, and thus is typically independent of process and temperature. The final state of the state machine that produces RBG may be used to control any resistor strings on the integrated circuit that need to be temperature and process independent. The calibration period may be repeated from time to time to track temperature variations.
An integrated circuit comprising a source of a calibration voltage, a current mirror providing a constant current source of a calibration current that is proportional to said calibration voltage and which flows through a calibration resistor having a controllable resistance;
An integrated circuit comprising a voltage source, a current mirror providing a constant current source, a calibration resistor comprising a string of resistors having constant switches across at least some of said resistors, a comparator, and a clocked control circuit;
A method of calibrating a resistor on an integrated circuit comprising:
Dependencies are inferred from the claim text.