84-GBd (168-Gb/s) PAM-4 3.7-Vpp Power DAC in InP DHBT for short reach and long haul optical networks
08 October 2015
In this Letter, we report on the architecture and performances of multilevel driver for Pulse Amplitude Modulation (PAM) formats, designed and fabricated in 0.7-um InP double-heterojunction bipolar transistor (DHBT) technology. The driver part is based on Power DAC architecture which is integrated with the multiplexing stage composed of three 2:1 selectors. Up to 100 GS/s operation was validated and PAM-2, -4, -8 signals with high amplitude were measured. In particular, PAM-4 at 84 GBd and PAM-8 at 64 GBd operation was demonstrated with respectively 3.7-Vpp and 4-Vpp differential output signal. This compact driver circuit is characterized by the highest merit factor in terms of high amplitude and the transmission capacity for an electronically generated multilevel signal.
