A 28Gbaud/s 4Vpp PAM4 MZ Modulator Driver in 0.13\mu \mathrm{m}$ SiGe BiCMOS Technology

Abstract

A 28Gbaud/s PAM4 large-swing optical modulator driver is designed in 0.13-\mu \mathrm{m}$ SiGe BiCOMS technology. The designed driver includes variable gain amplifier, continuous time linear equalizer and main driver stage. Group delay peak-peak value and bandwidth bottleneck from MZM are challenges to achieve high speed optical interconnect at 28Gbaud/s. A compensation technique of de-emphasis and pre-emphasis is also adopted to reduce group-delay variation and broaden bandwidth, respectively. Simulation results show that the driver features gain of 20dB, −3dB bandwidth of 25GHz by utilizing pre-emphasis circuit and CTLE, and it delivers a differential output swing of 4Vpp. The group-delay variation of the driver is 3.1ps by using de-emphasis circuit, which is less than ±0.1UI.