A 100 Gb/s DC-coupled optical modulator driver for 3D photonic electronic wafer-scale packaging

This paper presents a new DC-coupled differential driver for 3D photonic electronic wafer-scale packaging. The DC-coupling between the driver's output and a Mach-Zehnder modulator (MZM), overcomes the limitations of on-chip bias-Ts and achieves wideband RF performance. For the biasing and impedance matching it uses off-chip inductors as RF chokes and two on-chip 50 Ω resistors in series with a capacitor as the driver's differential termination. The proposed driver has independent voltage supplies for the differential branches, and each branch can be tuned between 4 V and 6 V separately to account for different modulations format and fabrication tolerance of MZMs. The designed distributed driver is realized in a 0.25 µm SiGe:C BiCMOS technology, and shows a 3-dB bandwidth of 50 GHz, 100 Gb/s PAM4 eye diagram and state-of-the-art 6.3 pJ/bit power efficiency in post-layout simulation.