A Low Power Quad 25.78-Gbit/s 2.5 V Laser Diode Driver Using Shunt-Driving in 0.18 µm SiGe-BiCMOS

We report on circuit design and measurement results of the newly developed quad 25.78-Gbit/s laser diode driver, fabricated by 0.18 μm SiGe-BiCMOS (ft/fmax =200/200 GHz). Power dissipation of the laser diode driver is only 40 mW/lane and 190 mW/lane including a laser bias current when the DFB laser is driven under 2.5 V supply. This IC is co-packaged with laser diodes in small size transmitter optical subassembly. We confirm excellent optical waveform, which is compliant with 100GBASE-LR4 optical eye specifications in IEEE802.ba.