A 4.6pJ/b 200Gb/s Analog DP-QPSK Coherent Optical Receiver in 28nm CMOS

Abstract

Emerging bandwidth-hungry applications such as cloud computing, have significantly driven the requirement for high transmission data rates. Polarization diversity coherent detection is an indispensable technique for realizing high-capacity transmission owing to its excellent spectral efficiency. ADC-DSP-based coherent receivers [1]–[2] have been widely deployed in long-haul optical systems, but the high power consumption prohibits their application in power-sensitive short-reach links like 5G mobile backhaul networks, arousing eagerness for power-efficient analog solutions. An analog coherent receiver is proposed in [3], where a single-stage equalizer is used to compensate for chromatic dispersion (CD) and rotation of state of polarization (SOP), resulting in complex inter-connection, large parasitic capacitance, and consequently limited data rate. In this paper, we present a 200Gb/s analog dual-polarization quadrature phase-shift keying (DP-QPSK) coherent optical receiver featuring a 2-stage equalizer to relax the speed limit, while consuming 10 times less power than ADC-DSP-based ones.