A fully automatic hierarchical compactor

ABSTRACT

A fully automatic hierarchical compactor has been developed to translate hierarchical, symbolic cell designs into artwork. The hierarchical compactor takes advantage of the fact that a typical hierarchical design uses the same cell in several different places. Each cell is first examined in all of its contexts. The leaf-cell compactor next compacts each leaf-cell to its minimum possible size in its worst-case environment. The last step is to abut instances of the cells according to the original symbolic layout; some grid line spacings may be increased to avoid breaking wires. The compactor is implemented as a set of rule-driven procedures that find all technology dependent information in technology description files. The result of this strategy is a technology-independent compactor that produces compact, error-free artwork.

REFERENCES

• ACKL83: ACKLAND, BRYAN AND NElL WESTE, "An Automatic Assembly Tool for Virtual Grid Symbolic Layout," Proc. VLSI '83 Norway, (Aug. 1983).
• BOYE83: BOYER, DAVID G. AND NElL H. E WEST~ "Virtual Grid Compaction Using the Most Recent Layers Algo~ rithm,' Proc. ICCAD-8$, (Sept. 1983).
• DANI85a: DANmL, STEPHEN, "Technology Independent Compaction for Symbolic Virtual-Grid Layouts," MCNC Technical Report {forthcoming} (Jan. ~985).
• DANI85b: DANn~ STEPHEN, "Rectilinear Anti- Feature Elimination by Polygon Algebra," MCNC Technical Report
• forthcoming: (Jan. 1985).
• OUST84: OUSTERHOUT, JOHN K~ "Comer Stitching: A Dam-Structuring Technique for VLSI Layout Tools," IEEE Trans. on CAD CAD-3(1) pp. 87-100 (Jan. 1984).
• ROSE83b: ROSENBERG, JONATHAN B. AND NElL H. E. WESTE, "ABCD - A Better Circuit Description," MCNC Tech. Rep. No. 4983-01, Microelectronics Center of NC, RTP, NC 27709 (Feb. 1983).
• SMIT85: SMITH, PHILIP O. AND STEPHEN W. DANIEL, 'l'he Master Technology Files System for Technology Independence," Proc. 22rid Design Automation Conf. {forthcoming}, (June 1985).
• WATA84: WATANABE, HtROYUK~, IC Layout Generation and Compaction Using Mathematical Optimization, Semiconductor Research Corporation, Research Triangle Park NC (February 1984).

INDEX TERMS

Primary Classification:
  B. Hardware
  B.7 INTEGRATED CIRCUITS
      B.7.1 Types and Design Styles
          Subjects: VLSI (very large scale integration)

Additional Classification:
  J. Computer Applications

General Terms:
Algorithms, Design, Performance, Theory