A 40-Gb/s 4-Vpp Differential Modulator Driver in 90-nm CMOS

In this letter, a 40-Gb/s optical modulator driver in 90-nm CMOS technology is presented. The design is based on the distributed amplifier (DA) topology with the proposed modified cascode stage to obtain high gain and large bandwidth, while also capable of protecting the MOS transistor under large output voltage swing. The modified cascode stage DA with enhanced high-voltage driving capability can reach an operating data rate up to 40 Gb/s with an differential output voltage swing of 4 V
_pp
(~3-V eye amplitude), which can be used for driving 50-Ω silicon modulators.