Patent ID: 7292637

Claim:
A communication system comprising: a. a differential transmitter having first and second differential output terminals transmitting a differential signal; b. a differential communications channel having: i. a first signal conductor coupled to the first differential output terminal; and ii. a second signal conductor coupled to the second differential output terminal; c. a differential receiver having a first differential input terminal coupled to the first signal conductor and a second differential input terminal coupled to the second signal conductor, the differential receiver receiving the differential signal from the differential transmitter via the differential communication channel; d. a common-mode transmitter having a first common-mode output terminal coupled to the first signal conductor and a second common-mode output terminal coupled to the second signal conductor, wherein the common-mode transmitter transmits a first common-mode signal component over the first signal conductor and a second common-mode signal component on the second signal conductor; and e. a common-mode receiver having: i. a common-mode extraction circuit having an extraction circuit input terminal coupled to the first signal conductor and an extraction circuit output terminal, the extraction circuit extracting a common-mode signal from at least one of the first and second common-mode signal components; and ii. a reference circuit having a reference-circuit input terminal coupled to the extraction circuit output terminal and a reference-circuit output terminal, the reference circuit deriving a common-mode reference signal from the common-mode signal and providing the common-mode reference signal on the reference-circuit output terminal.