The advent of cheaper and more powerful personal computers has not only expanded the user base; it is also creating a demand for greater transmission capacity among the telecom networks by adding an increasing volume of internet and videophone connections to the traditional phone and fax services. The following discussion of an OC 12/STM 4 receiver/transmitter chipset supports these developments and includes a description of the electronic components required for optic/electric (O/E) conversion in SDH/SONET fiber optic transmission systems.