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EPOXY: An Electrical and Physical Layout Optimizer that Considers Circuit Changes

Obermeier, Fred W.
Katz, Randy H.
Technical Report Identifier: CSD-87-388
November 1987

Abstract: Electrical performance and area improvement are important parts of the overall VLSI design task. Given designer specified constraints on area, delay, and power, EPOXY will size a circuit's transistors and will attempt small circuit changes to help meet the constraints. In addition, the system provides a flexible framework within which to evaluate the effects of different area and electrical models, as well as different optimization algorithms. Since the sum of transistor area is a better measure of dynamic power than cell area, an area model for standard-cell layout is presented. Optimization of a CMOS eight-stage inverter chain illustrates this difference; a typical minimum power implementation is 32.3% larger than the one for minimum area. The combination of a TILOS-style heuristic and augmented Lagrangian optimization algorithm yields quality results rapidly. EPOXY's circuit analysis is from 5 to 56 times faster than Crystal.