KNOWLEDGE BASED SYSTEM FOR DELAY OPTIMIZATION OF LOGIC CIRCUITS

Abstract

A Knowledge based system is a key technology for building advanced CAD system. Knowledge based techniques make it easy to adapt a system to different technologies. The system DOLKB (Delay Optimization Of Logic Circuits Using Knowledge Based techniques) proposed in this dissertation is one such approach. It optimizes the logic circuits (combinational and sequential circuits)for a specific target technology thereby improving the performance (speedwise) of the system. The optimization is done at gate level. The system performs substitutions of equivalent gate configurations and flip-flops, thereby reducing the overall propagation delay from input t.o output and improving the speed of the design. A knowledge based approach rather than algorithmic approach is used in order to provide a paradigm for the use of specialized knowledge about the target technology.The system uses a knowledge base of sixty four rules for achieving the performance.The logic simula.tor(not knowledge based) checks for the hazards & races in the circuit by taking actual delay of the elements used in the circuit into consideration.Thus the system proposed in thig dissertation is an approach towards solving one of the problems{i.e.delay optimization & timing verification)in the design of cell-based VLSI circuits and ASIC chips.