Receiver/transmitter input/output termination resistance calibration method

A method of receiver and transmitter input/output resistance calibration, using external reference resistor is presented in this paper. The proposed architecture produces a calibration code corresponding to 50-Ohm PVT compensated termination impedance, which is needed to avoid reflections in transmission lines. The presented calibration mechanism can be used in the special input/output circuits of several standards such as Peripheral Component Interconnect (PCI), Universal Serial Bus (USB), Double Data Rate (DDR) etc.