Link Training (LT) is performed after auto-negotiation (AN) converges to a backplane or copper technology. Technology selection can also be the result of a manual entry or parallel detection. Link training might be required due to frequency-dependent losses that can occur as digital signals traverse the backplane or a copper cable. The primary function of the LT IP core is to provide register information and a training sequence over the backplane link. The information is analyzed by a receiving circuit that is not part of the IP core. The other function of the IP core is to communicate training feedback from the receiver to the corresponding transmitter so that its equalizer circuit (not part of the IP core) can be adjusted as required. The two circuits comprising the IP core are the receive Link Training block and the transmit Link Training block.
Note: The logic responsible for the adjustment of the transmitter pre-emphasis
must be supplied external to this IP core.