A high frequency input buffer within an integrated circuit that is used to receive a signal from another integrated circuit is described. A preamplifier for use in an input buffer of the integrated circuit is described. The preamplifier includes a differential amplifier with differential input terminals and output terminals. An input data signal and an input reference signal are applied to the differential inputs. The differential output signals are generated in response to the differential input signals and are adapted to be applied to the differential input terminals of an amplifier within the input buffer. An adjusting device within the preamplifier adjusts the differential outputs such that they are in a region of optimum gain for the amplifier.