A 50Gb/s-PAM4 CDR with On-Chip Eye Opening Monitor for Reference-Level and Clock-Sampling Adaptation. - Chang Liu; Bozhi Yin; Tingyu Yao; Nan Qi; Dan Li 011; Jingbo Shi; Juncheng Wang; Hu Shang; Rui Bai 001; Patrick Yin Chiang (OFC, 2018)