Design of laser driver circuit

Abstract

Designing an Optoelectronic Integrated Circuit (OEIC) is an attractive field of research as it bridges the interface between electrical and optical components. The design of laser driver in optical transmitter is very critical because it requires large output current and high speed. To date, majority of laser drivers have been designed using Bipolar Junction Transistor (BJT) due to wider bandwidth and good quality of passive components. However, the standard digital Complementary Metal Oxide Semiconductor (CMOS) technology provides advantages, such as, low power, low cost of fabrication due to high production yield, and a higher degree of integration. Thus, the silicon CMOS technology, which is well known for low cost and high density, is preferred to design an Optoelectronic circuitry. Under this thesis, the work undertaken pertains to devising cascode-based laser driver circuit operating at 2.5 Gbps, using Hewlett Packard CMOS26G 0.8mm CMOS process. The devised circuit integrates well with the 1550nm rate equation based equivalent circuit model generated from R-soft design tool kit OptSim 3.6. This is definitely a step forward on the existing topologies, which have worked on 850nm VCSEL. The thesis projects reduction in number of transistors and, consequently, the chip area occupied by the driver. In nutshell, what has been done on this score and what remains to be done has been explained in detail in chapter-4 of the thesis under the title “conclusion & future scope”.