The need for simulation models that are reliable and able to predict the conceptual as well as the implementation errors early in the design process is a must in the current tight time to market constrains. In this paper; a model for a 1.25 Gb/s fiber channel transmitter is presented. The model is implemented using the IEEE 1076.1 standard VHDL-AMs. The modelled system is composed of two sections: an analog section, comprising the laser diode and the laser driver; and a digital section, consisting of an 8B/lOB encoder and a 1O:l multiplexe,: