TABLE OF CONTENTS Susmita Sur-Kolay
In physical design, floorplanning determines the topology of the layout, i.e., the relative positions of modules on the chip, based on the interconnection requirements of the circuit and estimates for area. A floorplan can provide a guideline in the detailed design of functional modules or blocks when the aspect ratios and pin positions of some of the modules on the chip are still unconstrained. Thus, floorplanning is important not only for physical design, but even more for choosing design alternatives in the early stages that are likely to produce optimal designs.
Placement was originally seen as a special case of floorplanning where the sizes and shapes of all the modules are known. In the history of computer-aided design (CAD) for very large scale integration (VLSI) circuits, the placement problem was addressed both for printed circuit boards as well as large scale integration (LSI) circuits. With the rapid increase in the scale of integration, the role of floorplanning came into the picture, particularly for the custom layout design style with variable width and height of modules. Some of the major techniques that were originally proposed for placement have subsequently been tailored for floorplanning.
The most significant difference between floorplanning and placement is in the modeling of the cells or modules. [*] The extra degree of...
