Orientation assignment of standard cells using a fuzzy mathematical transformation

In the VLSI standard cell design style, the main objective of the placement phase is to position a set of standard cells on the chip surface with a minimum area. Another advanced improvement, on the total wire length, can be made by flipping the standard cells after the placement phase. It is well known that minimizing the total wire length reduces the routing area in a standard cell placement. The orientation problem is to minimize the total wire length by assigning optimal orientations of standard cells. In this paper, based on fuzzy c-means clustering, we develop a fuzzy graph clustering algorithm to solve the orientation problem. The proposed approach has tested some standard cell placements, and produced a significant reduction of the total wire length