An 86.71875-GHz RF Transceiver for 57.8125-Gb/s Plastic Waveguide Links With a CDR-Assisted Carrier Synchronization Technique in 28-nm CMOS

This article presents an 86.71875-GHz RF transceiver IC featuring a fully integrated clock and data recovery (CDR)-assisted carrier synchronization loop (CSL) for waveguide links. The carrier frequency of 86.71875 GHz is chosen to be the third harmonic of the baseband null frequency of 28.90625 GHz, and the carrier synchronization is achieved using a baseband CDR instead of power-and area-intensive RF circuits. The IC, fabricated in 28-nm CMOS, demonstrates 57.8125-Gb/s pulse-amplitude modulation-4 (PAM-4) data transmission over a 1.5-m waveguide channel while improving the timing margin by 38% compared to conventional methods. The Tx and Rx ICs occupying an area of 1.98 × 0.95 mm² consume 190.1 and 117 mW at 57.8125 Gb/s, respectively. The test chip achieves the figure of merit (FoM) of 3.5 pJ/b/m in terms of throughput–distance and energy efficiency.