Digital Logic Testing and Simulation, 2nd Edition

CHAPTER 2

Simulation

2.1 INTRODUCTION

Simulation is an imitative process. It is used to study relationships between parameters that interact in a system. In some cases it may point out errors that cause a design to respond incorrectly. In other cases it permits optimization of a design for maximum performance or economy of operation or construction. In still other situations, the system may be so complex that simulation is the only way that variables affecting the design, and their interaction with each other, can be controlled and studied.

In order to imitate the behavior of a product or system, simulation employs models. A model is an imperfect replica. It must contain enough information to accurately represent the behavior of the variables of interest in the process or system being studied, but must not be so complex as to obscure details of the variables and their relationships or so intricate that its cost approaches that of simply building the device or system to be studied.

This chapter will focus on methods used to simulate digital logic circuits in order to predict their behavior in the presence of various stimuli and environmental factors. Note that the accuracy of the prediction of circuit response depends on the accuracy and level of detail of the circuit model provided to the simulator. In future chapters we will examine fault simulation and other methods for verifying ...