OUTPUT DRIVER WITH SLEW RATE CALIBRATION

摘要

An output driver for driving a data output signal through an output pad includes a plurality of calibration paths to calibrate the impedance of the output pad. Depending upon the desired impedance, various ones of the calibration paths are selectively coupled to the output pad. Each selected calibration path adds a capacitive load to a data node, which affects the slew rate for the data output signal. To adjust the capacitive load on the data node in light of the calibration path selections, the output driver includes a plurality of selectable capacitors corresponding to the plurality of calibration paths. If a calibration path is not selected to couple to the output pad, the corresponding selectable capacitor capacitively loads the data node.