A 10 Gb/s electro-absorption-modulator (EAM) driver using push-pull emitter followers and a cascoded output switch

A 10 Gb/s EAM driver was realized in a 0.2μ SiGe technology having a 60 GHz transition frequency. Fast switching was achieved with a cascoded output switch, while low voltage operation was assured using a tail resistor that generates the modulation current in conjunction with a common-mode feedback. Inductive peaking and PTAT biasing was used throughout the signal path, enhancing switching speed and minimizing temperature and process variation of the AC performances. The power dissipation was reduced with 30% by using push-pull emitter follower architecture. ICs main specifications are: supply voltage4.75-5.5V, modulation current 40-120mA, rise/fall time <25ps, deterministic jitter <15ps and die area 1.3×1.7mm².