Intel Corporation
Techniques to calibrate an impedance level

Abstract:

Examples described herein can be used to calibrate resistances provided by pull-up and pull-down circuits in an output driver circuit. A first reference voltage can be determined and applied to set a resistance level of a pull-up circuit to a desired level. A code for activating one or more transistor in the pull-up circuit can be determined against the first reference voltage. For a pull-down circuit, a second reference voltage can be set a resistance level of the pull-down circuit to a desired level. The resistance level of the pull-down circuit can be set to equal to the resistance level of the pull-up circuit. A second code can be set for activating one or more transistor in the pull-down circuit. The first and second reference voltages can be represented by index values. The code and second code can be stored for use by the pull-up circuit and pull-down circuit. Re-calibration of the pull-up and pull-down circuits can be performed to determine codes using the first and second reference voltages.