Abstract: An impedance matching system and a network for impedance matching at a driver circuit output for high frequency input-output devices. The impedance matching network comprises an adjustable-length transmission line having a length adjusted in proportion to the magnitude of transients on the driver circuit output and an input impedance, which is purely reactive, and is a function of its length. The purpose of the adjustable-length transmission line is to reduce transient voltages by providing a matching impedance for the reactive component of the impedance of the receiver circuit to the driver circuit. In the preferred embodiment, the impedance matching network comprises two parallel conductive lines formed on the system card, shorted by a movable stub, and connected in parallel to the driver circuit.