Functional Description

The SGMII PCS is a 1G or 2.5G full duplex interface. Each port accepts packet data from the MAC, performs GMII to 8B code group conversion, and performs 8B/10B encoding prior to passing the data to the SerDes module for transmission. The transmit path has an additional data buffer between the MAC and the PCS TX to decouple the PCS from the MAC, simplify clock tree insertion, and provide support 10/100M SGMII operation.

Each port on the receive path takes the unaligned data from the relevant SerDes module, re-aligns each lane to the correct 10B boundary, decodes the data, converts the resulting 8B codewords into GMII traffic, and passes the data through a clock tolerance compensation buffer. This data is then passed to the MAC through a 16-bit GMII interface.