On-Chip Filter for Mitigating EMI-Related Common-Mode Noise in High-Speed PAM-4 Transmitter.

The electromagnetic interference (EMI) is generated by the common-mode (CM) noise in differential circuits and has a high risk of degrading other circuits’ performance by radiating the disturbance. This paper demonstrates an on-chip filter that suppresses the CM noise while keeping the integrity of the differential-mode (DM) signal. Based on the delay equalizer, this filter provides the benefit of whole spectrum DM constant resistance, which achieves great matching between the off-chip transmission line and the on-chip circuit. The simulation results show that the filter efficiently mitigates the EMI of a 56 Gbps PAM-4 transmitter by suppressing the CM noise up to 18.85 dB at 28 GHz with core area of 207 μm × 125 μm.