A 42.7Gb/s Optical Receiver with Digital CDR in 28nm CMOS

This paper presents a broadband optical receiver that employs multiple bandwidth extension techniques in the analog front-end (AFE) and has efficient digital clock and data recovery (CDR). Total AFE bandwidth is extended by 5.5X with continuous-time linear-equalizer (CTLE) peaking, series inductances between each AFE stage, and active inductors in the CTLE output and variable gain amplifier (VGA) stages. The resolution of a digitally controlled oscillator (DCO) is optimized at 9-bit to balance quantization and random noise-induced jitter from the CDR. Fabricated in 28nm CMOS, the 42.7Gb/s optical receiver achieves an optical modulation amplitude (OMA) sensitivity of -3.6dBm at a bit error rate (BER)<10-12, 10MHz CDR bandwidth, and 3.4pJ/bit energy efficiency.