A 28 Gb/s Multistandard Serial Link Transceiver for Backplane Applications in 28 nm CMOS

Abstract

This paper presents a power- and area-efficient multistandard serial link transceiver designed for backplane application rates of up to 28 Gb/s, such as OIF CEI-25G, CEI-28G, and IEEE 802.3bj 100G-KR4. The receiver features a continuous-time linear equalizer, variable gain amplifier, and a 14-tap decision feedback equalizer, including eight floating taps. The transmitter has a 2:1 multiplexer with a duty cycle distortion corrected half-rate clock and a full-rate source-series terminated driver with a 5-tap feed-forward equalizer. The shared PLL employs a transformer-based LC-VCO that achieves a VCO tuning range of 20G to 29 GHz and 0.23 ps RMS jitter at 28.125 GHz. The transmitter output shows only 50 fs duty-cycle distortion. The transceiver can compensate a 40 dB insertion loss backplane channel (excluding package) at a data rate of 25.78 Gb/s with eight channels running simultaneously. It is fabricated in 28 nm standard CMOS and analog section consumes only 295 mW at 1 V supply with transmitter driver at 1.25 V. Such low power consumption and performance are achieved by combination of advanced 28 nm process, low power and performance driven receiver and transmitter topologies, widely adopted bandwidth extension techniques, built-in analog calibrations and one common PLL with a transformer based VCO for four transceivers.