Quasi dynamic approach to layout compaction

Introduction to VLSI systems

Physical Design Automation of Vlsi Systems

A popular algorithm to compact VLSI symbolic layout is to use a graph algorithm similar to finding the "longest path" in a network The algorithm assumes that the spacing constraints on the mask elements are of the lower bound type However, to enable the user to have close control over the compaction result, a desired symbolic layout system should allow the user to add either the equality or the upper bound constraints on selected pairs of mask elements as well This paper proposes an algorithm which uses a graph-theoretic approach to solve efficiently the compaction problem with mixed constraints

An Algorithm to Compact a VLSI Symbolic Layout with Mixed Constraints

Free form or "stick" type symbolic layout provides a means of simplifying the design of IC subcircuits. To successfully utilize this style of layout, a complete design approach and the necessary tools to support this methodology are required. In particular, one of the requirements of such a design method is the ability to "compact" the loosely specified topology to create a set of valid mask data. This paper presents a new compaction strategy which uses the concept of a virtual grid. The compaction algorithm using the virtual grid is both simple and fast, an attribute which allows the designer to conveniently interact with the algorithm to optimize a layout. In addition to the compaction algorithm, methods used to create large building blocks will be described. The work described here is part of a complete symbolic layout system called MULGA which is written in the C programming language and resides on the UNIX operating system.

Virtual Grid Symbolic Layout

Symbolic layout and compaction is reaching a mature status. This is demonstrated, in part, by the recent or imminent introductions of a number of commercial symbolic layout and compaction systems. The two most frequently used symbolic layout compaction approaches, constraint graph compaction and virtual grid compaction, are reviewed in this paper. The current status of these two approaches is presented by looking at the results of the ICCD87 compaction benchmark session.

Quasi dynamic approach to layout compaction

References

Introduction to VLSI systems

Physical Design Automation of Vlsi Systems

An Algorithm to Compact a VLSI Symbolic Layout with Mixed Constraints

Virtual Grid Symbolic Layout

Symbolic layout compaction review

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