Comparisons of Equalization Performances and CM Suppression on NRZ and PAM4 Signals using Wideband DME-CMF

In this paper, the difference between the NRZ signal equalization and the PAM4 signal equalization of a circuit with dual function of differential mode equalizer and common mode filter (DME-CMF) is discussed, and a verification of common mode suppression in time domain is carried out. To evaluate NRZ and PAM4 differential equalizations, definitions of effective equalization bandwidth and normalized eye height are proposed and the DME-CMF is proven to maintain a better quality for PAM4 signals than for NRZ signals. For common mode suppression, a time-domain simulation is conducted and a definition of common mode suppression capability is provided to demonstrate that the DME-CMF has significant common mode suppression on both NRZ and PAM4 signals.