Self-calibration method for input/output termination resistance variation elimination

A method of on-die resistance self-calibration for receiver and transmitter Input/Output devices, without external reference resistor is presented. Resistance mismatch elimination method, using reference clock and dc current is provided. The proposed method provides opportunity to measure the difference of the termination resistor and the transmission line impedance which is assumed 50-Ohm, detect the variation and minimizing it. A self-calibration technique for termination resistors mismatch elimination is implemented.