A Monolithically-Integrated Optical Receiver in Standard 45-nm SOI

Integrated photonics has emerged as an I/O technology that can meet the throughput demands of future many-core processors. Taking advantage of the low capacitance environment provided by monolithic integration, we developed an integrating receiver front-end built directly into a clocked comparator, achieving high sensitivity and energy-efficiency. A simple model of the receiver provides intuition on the effects of wiring and photodiode capacitance, and leads to a photodiode-splitting technique enabling improved sensitivity at higher data rates. The receiver is characterized in situ and shown to operate with μA-sensitivity at 3.5 Gb/s with a power consumption of 180 μ W (52 fJ/bit) and area of 108 μm² . This work demonstrates that photonics and electronics can be jointly integrated in a standard 45-nm SOI process.