A 3.8 mW/Gbps Quad-Channel 8.5–13 Gbps Serial Link With a 5 Tap DFE and a 4 Tap Transmit FFE in 28 nm CMOS

This paper presents a quad-lane serial transceiver that supports virtually all data center communication standards around 8.5–13 Gbps, implemented in 28 nm CMOS technology. The transmitter consists of 20:2 mux followed by a half-rate source-series terminated (SST) driver embedded with a 4 tap FFE and an analog equalizer. The receiver has an adaptive CTLE, 5 tap DFE, and fully digital CDR followed by 2:20 demux. At 13 Gbps, the transceiver can equalize 35 dB Nyquist loss at BER of 10-12. At 1.0 V supply, the transceiver consumes 49 mW/lane at 13 Gbps rate with full equalization capability. An LC VCO-based fractional PLL provides the clocking to quad TX/RX lanes using a low-power inductively tuned clock routing channel. The transceiver architecture not only enables the baud rate operation from 8.5 to 13 Gbps but also supports a wide range of oversampled subrates. This work represents the lowest reported power in its class to date, and the transceiver is suitable for many applications due to its comprehensive flexibility and power efficiency.