A 32 Gb/s, 201 mW, MZM/EAM Cascode Push–Pull CML Driver in 65 nm CMOS

This brief presents a 32 Gb/s driver for a Mach–Zehnder modulator (MZM) and an electro-absorption modulator (EAM). A push–pull current-mode logic driver is chosen to achieve a better power efficiency and a large voltage swing. A double cascode with thin oxide transistors is employed to mitigate the over-voltage stress associated with a large output voltage swing. At the same time, shunt-peaking inductors are incorporated in a compact way to extend the bandwidth and to have a flat group delay. The proposed driver has been fabricated using 65 nm CMOS technology with an active area of 0.086 mm 2 . The electrical measurement result shows that the driver exhibits a differential output swing of 4 ${\text V}_{\text {pp}}$ at 10 Gb/s. The measured extinction ratios of the driver using the MZM and EAM are 4.53 dB and 4.17 dB, respectively, at 32 Gb/s. The power consumption is 201 mW at 32 Gb/s, which corresponds to an energy efficiency of 6.28 mW/Gb/s.