Automatic Routing of Integrated Circuit Connections: a Tutorial

Before any two entities can communicate, there must exist a physical medium across which the communication can take place. In an integrated circuit, this medium takes the form of electrical connections between various parts of the circuit. Although these electrical connections can be created by hand, the process is time consuming, boring, and prone to error. For some circuits, creating the electrical connections (or routing as it is usually called) can take considerably more time than designing the active elements of the circuit. Because of this, the automatic routing was one of the first problems to be addressed by design automation. The area and timing (and hence the cost and performance) of an integrated circuit is directly dependent on the quality of the routing. Hence automatic routing has been extensively researched, and the body of literature is enormous. So much so that a list of just the basic references would require a bibliography much larger than this paper. In a paper of this size, it is impossible to give even a brief introduction all of the existing techniques. The reader is referred to [1] for a more detailed introduction to this subject, and a more extensive bibliography of the basic papers.