A VERSATILE SI-BIPOLAR DRIVER CIRCUIT WITH HIGH-OUTPUT VOLTAGE SWING FOR EXTERNAL AND DIRECT LASER MODULATION IN 10 GB/S OPTICAL-FIBER LINKS

A monolithic integrated driver circuit developed for laser modulation in a 10 Gb/s optical-fiber link is presented. The IC was fabricated in a self-aligned double-polysilicon Si-bipolar production technology with f(T) almost-equal-to 25 GHz. The circuit can be operated up to 14 Gb/s with a maximum output voltage swing as high as 3.6 V at 50 OMEGA load (corresponding to an internal current swing of 108 mA), which allows the circuit to drive external modulators. In addition, the circuit can be used for direct laser modulation at 10 Gb/s, since the output current swing can easily be controlled over a wide range (e.g., from 15 mA to 60 mA). Problems in the design of such driver circuits as well as their solutions are discussed in detail.