Leaf Cell and Hierarchical Compaction Techniques

Leaf Cell and Hierarchical Compaction Techniques 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 Leaf Cell and Hierarchical Compaction Techniques is three-fold. First, new 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. Second, 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. Third, 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.
From the Foreword:
`...In this book, the authors provide a comprehensive approach to compaction based on carefully conceived abstractions. They describe the design of algorithms that provide true hierarchical compaction based on linear programming, but cut down the complexity of the computations through introduction of innovative representations that capture the provably minimum amount of required information needed for correct compaction. In most compaction algorithms, the complexity goes up with the number of design objects, but in this approach, complexity is due to the irregularity of the design, and hence is often tractable for most designs which incorporate substantial regularity.
Here the reader will find an elegant treatment of the many challenges ofcompaction, and a clear conceptual focus that provides a unified approach to all aspects of the compaction task...'
Jonathan Allen, Massachusetts Institute of Technology