A CMOS Photonic Optical PAM4 Transmitter Linearized using Three-Segment Ring Modulator

A scheme to realize Optical PAM-4 transmitter by driving a three-segment microring modulator with tunable voltage-mode drivers is presented. This proposed scheme provides linearly spaced PAM-4 levels and is further categorized into two schemes, namely higher "0" and lower "1" tuning. The two schemes are verified using co-simulation of voltage-mode drivers implemented in 65nm CMOS and Verilog-A compact models for photonic components based on a silicon photonic process from IMEC. Also, the robustness of our proposed scheme can be proved by achieving high linearity when phase-shifter length variation is present.