US Patent 7729429 Active replica transformer hybrid

A communication circuit comprises a near end transmitter, and adjustable near end replication transmitter and a near end receiver. The near end transmitter is configured to generate a transmission signal and comprises a first plurality of current sources. Outputs of the first plurality of current sources are summed to generate the transmission signal. The adjustable near end replication transmitter comprises a second plurality of current sources. Outputs of the second plurality of current sources are summed to generate a replication signal in accordance with the transmission signal. The replication signal from the adjustable near end replication transmitter is subtracted from the transmission signal from the near end transmitter and a received signal from a communication channel to generate a subtraction signal. The near end receiver is configured to receive the subtraction signal.