Leaf Cell and Hierarchical Compaction Techniques

This text presents novel algorithms developed for the compaction of large layouts. These algorithms have been implemented as part of a system that has been used on many industrial designs. The focus of the book is three-fold. Firstly, ideas for compaction of leaf cells are presented. These cells can range from small transistor-level layouts to very large layouts generated by automatic place and route tools. Secondly, new approaches for hierarchical pitchmatching compaction are described and the concept of a minimum design is introduced. The system for hierarchical compaction is built on top of the leaf cell compaction engine and uses the algorithms implemented for leaf cell compaction in a modular fashion. Thirdly, a new representation for designs called "Virtual Interface", which allows for efficient topological specification and representation of hierarchical layouts, is outlined. The "Virtual Interface" representation binds all of the algorithms and their implementations for leaf and hierarchical compaction into an intuitive and easy-to-use system.