A 16-Gb/s -11.6-dBm OMA Sensitivity 0.7-pJ/bit Optical Receiver in 65-nm CMOS Enabled by Duobinary Sampling

Abstract

High-speed, low-power optical interconnects, such as intensity modulation direct detection (IMDD) optical links, are increasingly deployed in data centers to keep pace with the growing bandwidth requirements. High-sensitivity low-power optical receivers (RXs) are the key components that enable energy-efficient IMDD optical interconnects. This article presents a low-power nonreturn-to-zero (NRZ) optical RX using a combination of a limited-bandwidth trans-impedance amplifier (TIA) and duobinary sampling to improve RX sensitivity at high data rates. Duobinary sampling leverages the well-controlled TIA inter-symbol interference (ISI) to recover the transmitted data, making it much more hardware efficient than canceling the ISI using a decision feedback equalizer (DFE). The proposed optical RX employs a CMOS-based analog front-end (AFE) to achieve high linearity and excellent power efficiency. Fabricated in 65-nm CMOS process, the prototype RX achieves optical modulation amplitude (OMA) sensitivity of -11.6 dBm at 16 Gb/s with 0.7-pJ/bit efficiency.