An Extremely Linear, 33 GHz Bandwidth Mach-Zehnder Modulator Driver Based on Closed-Loop Topologies in 28nm CMOS

In this work, the design of a linear Mach-Zehnder modulator driver for coherent optical communications is presented. The design, based on transconductor-transimpedance closed-loop topologies, achieves very low distortion, opening the way to the use of complex modulation formats. The measured Total Harmonic Distortion (THD) for 1.5 V peak-to-peak differential <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\mathrm{V}_{\text{ppd}})$</tex> output swing at 1 GHz is 0.85 %, with a -3 dB bandwidth of 33 GHz and a continuously-programmable gain ranging from 10 dB to 20 dB. The overall power consumption is 204 mW, with a single supply voltage of 2.4 V. The chip has been fabricated in 28 nm CMOS technology, demonstrating the feasibility of both high performances, greater integration, and lower costs.