A 50 Gb/s PAM-4 Optical Modulator Driver for 3D Photonic Electronic Wafer Scale Packaging

This paper presents the design and measurement of a 50 Gb/s PAM-4 optical modulator driver in a $0.25\ \mu \text{m}$ SiGe:C BiCMOS process and analyzes the RF performance of a new photonic-electronic wafer scale packaging technology and its impact on the eye diagram of the driver. In the new wafer scale packaging technology $7\ \mu \text{m}$ through polymer vias are created to connect an InP photonic wafer to a Silicon electronic wafer. The new through polymer vias with their small size, high density, low parasitics and strong mechanic reliability are suitable for high data rate optical communication up to 130 GBaud. A linear optical modulator driver has been designed and fabricated. It has 15 dB of gain with a 3 dB bandwidth of 24 GHz, delivers 3.2 V differentially at 50 Gb/s PAM-4 and consumes 400 mW, resulting in a figure of merit of 8 pJ/bit.