High-Speed Transmitters in 90nm CMOS for High-Density Optical Interconnects

Small, high-speed and low power optical transmitter circuits are needed for optical interconnects to play a role in improving chip I/O bandwidth. This paper demonstrates two different transmitter designs fabricated in a 1V 90nm CMOS technology, one suitable for driving vertical cavity surface emitting lasers (VCSELs) and the other for driving multiple quantum well modulators (MQWMs). A four-tap current summing FIR equalizer extends VCSEL data rate for a given average current. It consumes 80mW at 18Gb/s operation and occupies 0.03mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2 </sup> area. The MQWM transmitter has a pulsed-cascode output stage capable of supplying a voltage swing of twice the 1V supply without overstressing thin-oxide core devices. It consumes 38mW at 16Gb/s and occupies 0.014mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> area