Design, modelling and characterization of a 3-Vppd 90-GBaud over-110-GHz-bandwidth linear driver in 0.5-um InP DHBTs for Tb/s optical communications

In this article, we present the modelling, design, fabrication and characterization of a 3-Vppd linear-output-swing 90-GBd PAM-4 modulator driver, realised in III-V Lab inhouse 0.5-um InP DHBT technology (380/520-GHz fT/fMAX, 4.2- V BVCE0). The driver exhibits 13-dB equalisation capabilities at 95 GHz with a bandwidth well beyond 110 GHz which, to the best of our knowledge, is the highest in current state-of-the-art. It features 0.67-W power consumption, resulting in a 1.5-GBd FoM with good output signal quality. To the best of our knowledge this is the highest PAM-4 >64 GBd performance reported to date, although no DSP nor pre-emphasis was used. We also report on the new 0.5-um InP DHBT technology and its modelling using small-value external parasitic EM-simulation extraction, yielding improved high-frequency accuracy at DHBT- and circuit-level