An apparatus comprising a first differential output driver to provide a single ended output voltage in response to an input voltage, a second differential output driver to provide a single ended output in response to the input voltage where the first output voltage and the second output voltage are representative of the positive and inverted input voltage. The apparatus also includes a feedback circuit to monitor the first and second output voltages and apply a bias voltage to at least one of the first and second output drivers to vary the point where the first and second output voltages cross-over as the input voltage changes from a first to a second level.