An output amplifier is provided for use in a bidirectional communications
interface, for example, connecting a transmitter and a receiver to a
transmission line. The output amplifier includes a differential amplifier
pair connected to output circuitry. The differential amplifier pair
receives differential data signal pairs from each of a transmission line
and a transmitter. The output circuitry receives signals from the
differential amplifier pair and, in response, forms single-ended output
logic signals. The output amplifier suppresses electronic input noise
throughput using an asymmetric transfer characteristic that offsets
output signal logic levels with respect to input noise signal levels. The
asymmetric transfer characteristic is produced by skewing a transfer
characteristic of the differential amplifier pair using an asymmetrical
transistor configuration at an output side of the differential amplifier
pair. The output logic signals represent data received on the
transmission line, and are provided to the receiver.