REST: A Leaf Cell Design System

Abstract

This thesis describes a leaf cell design system, REST, Richard's Editor for Sticks. REST is intended to be used for the preparation of the lowest level cells in an integrated circuit design. A stick notation is used in the editing process. Given a structured design methodology any design task can be separated into two parts: 1) leaf cell design and 2) composition cell design. This tool addresses the first of these tasks, although it may also be used for general manipulation of stick diagrams. A table driven compaction algorithm is presented. This graph based algorithm uses a weighted affinity factor to reduce total polysilicon and diffusion wire length. A suite of utilities provide functions such as file interface, physical mapping, annotation, etc. consistent with a set of design rules. The system has been implemented in Simula on a DEC 20 computer, and works in conjunction with a limited functional diagramming system. The design rules, models and stick interpretation are table driven and can be changed for various technologies. Currently REST is being used for NMOS technology. A community of users have used the REST system to prepare a number of designs resulting in a substantial reduction of design time. In addition, the system is currently being used at a major computer manufacturer in conjunction with a VLSI design course.