6.5 A 400Gb/s Transceiver for PAM-4 Optical Direct-Detect Application in 16nm FinFET

PAM-4 has become the mainstream modulation format for short-reach ($\lt2$ km) optical interconnects at data rates of 50Gb/s and above [1, 2]. For more efficient utilization of optical bandwidth in large-scale data centers, data rates of 100Gb/s per wavelength are required. This data rate imposes aggressive requirements on transceiver bandwidth (BW) and jitter. In addition, due to thermal constraints, transceivers must consume low power to help meet optical module power budgets specified by the multisource agreements (MSA) such as QSFP-DD and OSFP. This paper presents a low-power and low-jitter 4 × 100Gb/s transceiver for PAM-4 optical interconnects.