A fast and accurate technique to optimize characterization tables for logic synthesis

Cell characterization data is used by synthesis and timing verificationtools to compile and validate a cell netlist which meets timingconstraints imposed by the designer. Characterization tablescontain data for multiple, simple equations representing a cell's behaviorand are an alternative to the single, monolithic characteristicequation. Data in the table is fit to a function whose form isfixed by the application, and the cellýs response is interpolated fromthe function. Tables can potentially increase accuracy, but large tablescan cause a program to use dramatically more memory and runmuch slower. The optimization of characterization tables, in whichaccuracy is maintained but table size is significantly reduced, is importantif large programs, such as synthesis, are to complete accuratelyand in a reasonable runtime. In this paper we address someof the issues involved in characterizing cells and optimizing characterizationtables quickly and accurately. Experimental results fromthe use of these techniques within AMD for a Synopsys cell libraryis also presented.