Design Closure - Evolution of The Design Closure Flow

Evolution of The Design Closure Flow

Designing a chip used to be a much simpler task. In the early days of VLSI, a chip consisted of a few thousand logic circuits that performed a simple function at speeds of a few MHz. Design closure was simple: if all of the necessary circuits and wires "fit", the chip would perform the desired function.

Modern design closure has grown orders of magnitude more complex. Modern logic chips can have tens to hundreds of millions of logic elements switching at speeds of several GHz. This improvement has been driven by Moore’s law of scaling of technology, and has introduced many new design considerations. As a result, a modern VLSI designer must consider the performance of a chip against a list of dozens of design constraints and objectives including performance, power, signal integrity, reliability, and yield. In response to this growing list of constraints, the design closure flow has evolved from a simple linear list of tasks to a very complex, highly iterative flow such as the following simplified ASIC design flow: