Abstract: An integrated circuit driver for providing data to a communications channel comprises first and second output buffers coupled to first and second output conductors (e.g. bondpads) respectively. Each output buffer comprises a multiplicity of pull-up transistors and a multiplicity of pull-down transistors coupled to the associated output conductor through pull-up resistors and pull-down resistors, respectively. A multiplicity of delay circuits coupled to a data input node supply delayed data signals to the control terminals of the pull-up and pull-down transistors. Control circuitry is included for selectively activating the delay circuits. In a typical case, the control circuitry comprises multiplexers each having an output that is coupled to the input of a corresponding delay circuit. Advantages of the technique include a constant output impedance and waveshaping of the data output for reduction of harmonics.