Embodiments are described for an output driver circuit capable of maintaining a substantially constant output impedance across a wide range of output voltages. The driver circuit includes a pull-up circuit and a pull-down circuit, each having two or more current paths that either source currents to or sink currents from the output node. The addition of the third current path provides additional current such that the sum of the total currents have a magnitude that changes linearly as the output voltage at the output node is being driven.