5.2.2 EQ Near-End Loopback
(Ask a Question)Near-end serial loopback (transmitter to receiver) or EQ NELB uses the digital serialized transmit data that bypasses the transmit output buffer and loops the data back to the third-stage CTLE input, bypassing the receiver input and connecting to the CDR only.
The EQ NELB mode does not test the transmit buffer, high-speed receive buffer, low-speed receive buffer, CTLE stages 1 and 2 for the CDR, CTLE stages 1, 2, and 3 for the DFE and eye monitor circuits.