EPEPS 2019: Montreal, Canada
Tutorial IV
Simulation to Measurement Challenges on PAM4 for 400GB Ethernet

Hee-Soo Lee, Lead Application Developer/SerDes Product Owner, Keysight Technologies

Data rates are going to grow exponentially towards 2020 and beyond. Since the late 1990's data rates have increased from 1 Gbps to today's top speeds of ~50 Gbps per channel. In order to support this significant increase in speed, different kinds of transmission modulation like PAM4, PAM8, PAM12, Duo-binary, etc. are evolving. Most high speed serial links are designed to run with differential signaling because of the virtues of data throughput and simplicity, such as embedded clocking. The key to differential signaling is to maintain the symmetry of voltage waveforms seen by the receiver. However, due to manufacturing tolerances and asymmetric nature of dielectric medium, imbalance in signaling for cables, connectors, and PCBs is inevitable such that it causes intrapair skew and mode-conversion that degrade the channel performance. This presentation demonstrates a systematic EDA simulation solution to examine how much mode conversion and skew may be allowed for systems at 25 Gbps and beyond.