A 10 Gb/s, 120/60 mA laser/modulator driver IC with dual-mode actively matched output buffer

A Laser Driver IC for 10 Gb/s --SONET OC-192-- fiber optic transmitters is described. Depending on the user application, the IC is capable of driving up to 120 mA of current into a laser diode or 60 mA into an electro-absorption or Mach-Zehnder modulator with rise and fall times below 25 pS. In both cases the driver provides a DC-coupled back termination of either 25 or 50 Ω, implemented by means of a novel dual-mode actively matched output buffer which allows the power consumption of the IC to remain at a minimum and which makes the IC most suitable for co-packaging with uncooled lasers and electroabsorption modulators. The driver is fabricated in a 0.25 µm production GaAs PHEMT process with substrate thru vias, thin film resistors and MIM capacitors.