A 50-Gb/s PAM4 Si-Photonic Transmitter With Digital-Assisted Distributed Driver and Integrated CDR in 40-nm CMOS

A 50-Gb/s four-level pulse-amplitude modulation (PAM4) silicon photonic transmitter is presented, which is composed of a 40-nm bulk CMOS driver hybrid integrated with a 180-nm silicon-on-insulator (SOI) CMOS Mach-Zehnder modulator (MZM). To recover and demodulate 50-Gb/s PAM4 data into dual-25-Gb/s nonreturn to zero (NRZ) streams for the co-designed MZM digital-analog converter (DAC), a reference-...