Performance-Driven Placement of Cell Based IC´s

The increasingly important role of the interconnect in the timing performance of present and future integrated circuit technologies underscores the need to reconsider conventional physical design CAD tools, and devise new ways to influence performance during layout. Interconnects are not perfect conductors, they introduce parasitic elements that load the logic gates and distort the temporal properties of the design as viewed by the logic designer. Cell placement that minimizes wirelength as the sole objective does not solve the problem, leaving a margin for performance improvement that has not been fully exploited. This paper presents a novel approach to performance-driven placement, combining timing analysis and physical design to dynamically optimize the performance of the chip during placement. The ideas are embodied in a program named Allegro, and preliminary results tested on Sea-of-Gate designs are encouraging.