8.7 A 112Gb/s ADC-DSP-Based PAM-4 Transceiver for Long-Reach Applications with >40dB Channel Loss in 7nm FinFET

Driven by the proliferation of rich media services and a drastic increase of data availability, the demand for high-speed data transfer in the data center continues to grow at greater than 26 percent year-over-year [1]. This urges the imminent solution of top-of-rack switches in hyperscale networks with faster I/O interfaces to simultaneously support both low power and high throughput. Supporting the substantial bandwidth increase has driven the development of new electrical and optical interconnect standards which enable 100Gb/s per channel including IEEE 802.3ck and CEI-112G with PAM-4 modulation in conjunction with forward error correction (FEC) [2]. For long-reach applications, a transceiver architecture with >40dB channel equalization is critical due to the extra 8-10dB package insertion loss. To resolve those bottlenecks, this work presents an ADC-DSP based PAM-4 transceiver capable of equalizing >41.5dB lossy channels and achieving 112Gb/s per channel and 896Gb/s overall retimer throughput in 7nm FinFET.