Technique for cancelling common mode switching noise to achieve reduced error rates in a local area network

摘要

Improved gain control is obtained in each receiver of a LAN interface or hub in a LAN of the type using amplitude critical signals for conveying information. An evaluation circuit compares a signal representing a calibration value to a predetermined limits and adjusts the gain by one of a plurality of amplification levels to maintain a high level signals which are more accurately decoded into digital information. Improved noise cancellation is also obtained by creating a primary copy and an inverted copy of the received amplitude critical signal, amplifying the primary and inverted copy signals by the same predetermined amount and adding the amplified signals. The addition reinforces the value of the received amplitude critical signal while effectively subtracting the noise effects.