Design of 20Gb/s PAM4 Transmitter with Maximum Transition Elimination and Transition Compensation Techniques

초록

In this paper, a pulse amplitude modulation 4-level (PAM4) transmitter with maximum transition elimination (MTE) and transition compensation technique is presented. In the PAM4 signal, inter-symbol interference (ISI) and crosstalk noise are more affected by the maximum transition than the middle or the minimum transition. The proposed PAM4 transmitter uses a encoder mapping data into maximum transition eliminated data. The proposed PAM4 transmitter also uses the transition compensation (TC) technique with an additional logic and driver expanding a middle eye in a output eye-diagram to balance middle eye with top, bottom eye. Compared to the original PAM4 transmitter, the top and the bottom eye height and width of the PAM4 transmitter with MTE encoder are expanded about 50%. With TC technique, the difference between eyes areas is reduced to less than 15%.