A DC-95GHz, 4-channel M-Z modulator driver with >4V ppd output and 4.2GBd FoM in 22nm FD-SOI CMOS

Abstract: Coherent optical transmitters supporting new applications demanding Tb/s data rates employ quad Mach-Zehnder modulators (MZMs) and electronic drivers [1]. A 4-channel, broadband linear modulator driver supporting I-Q (e.g., DP-16QAM) and PAM-4 modulation at rates exceeding 100 GBaud (e.g., $200 \mathrm{~Gb} / \mathrm{s}$ PAM-4) in 22 nm FD-SOI CMOS technology is described in this paper. The CMOS driver achieves a differential linear output swing of $\gt 4 \mathrm{~V}_{\text {ppd }}$ into $60 \Omega$ and 95 GHz bandwidth with $17 \pm 2$ ps group delay below 60 GHz. It meets the requirements of both silicon photonic-IC MZMs $(40 \mathrm{GHz}$ BW [2]) and external MZMs (e.g., InP $70-90 \mathrm{GHz}$ BW [3]). Driver bandwidth is extended $3.6 x$ by an on-chip L-C filter, which provides gain peaking and compensates external losses in a transmitter.