22.2 A 25Gb/s hybrid integrated silicon photonic transceiver in 28nm CMOS and SOI

Abstract

Integrated photonic interconnect technology is free from the bandwidth-distance limitation that intrinsically exists in electrical interconnects, promising a disruptive alternative for next-generation scalable data centers. Silicon photonic platforms have been reported based on monolithic and hybrid integration. Monolithic systems mitigate integration overhead but require compromise in either electronic or photonic device performance [1,2]. Hybrid integration allows for independent process selection for each device so that overall system can potentially achieve the best performance [3]. This paper presents a hybrid integrated electrical-optical (E-O) interface including a driver/TIA chip in 28nm CMOS and a modulator/PD chip in SOI, based on a mixed-pitch bumping technology. A pseudo-differential driver with pre-emphasis enables an 800MHz bandwidth (BW) carrier-injection ring modulator to operate at 25Gb/s with power efficiency of 2.9pJ/b. A TIA implements two BW-enhancement techniques: a regulated-cascode (RGC) input stage with shunt-shunt feedback and T-coil inductive peaking, and a hybrid offset calibration, achieving 25Gb/s with power efficiency of 2.0pJ/b and a sensitivity of -8.0dBm OMA.