There is disclosed, for use in an integrated circuit, an apparatus for driving a signal line in the integrated circuit. The apparatus comprises: 1) a line driver for receiving an incoming data signal and transmitting an outgoing data signal on the signal line; 2) a power source for supplying a plurality of power voltage levels to a power supply rail of the line driver; and 3) a power level controller for determining a data rate of the outgoing data signal and in response to the determination, selectively applying one of the plurality of power voltage levels to the power supply rail of the line driver to thereby modify an amplitude of the outgoing data signal.