A new approach for rules-based optical proximity correction is presented.The discussion addresses on how to select and construct more concise and practical rules-base as well as how to apply that rules-base.Based on those ideas,several primary rules are suggested.The v-support vector regression method is used to generate a mathematical expression according to rule data.It enables to make correction according to any given rules parameters.Experimental results demonstrate applying rules calculated from the expression match well with that from the rule table.
A new approach of incremental placement approach is described.The obtained timing information drives an efficient net-based placement technique,which dynamically adapts the net weights during successive placement steps.Several methods to combine timing optimization and congestion reducing together are proposed.Cells on critical paths are replaced according to timing and congestion constraints.Experimental results show that our approach can efficiently reduce cycle time and enhance route ability.The max path delay is reduced by 10% on an average afterincremental placement on wirelength-optimized circuits.And it achieves the same quality with a high speed up compared to timing driven detailed placement algorithm.
A new incremental placement algorithm C-ECOP for standard cell layout is presented to reduce routing congestion.It first estimates the routing congestion through a new routing model.Then,it formulates an integer linear programming (ILP) problem to determine cell flow direction and to avoid the conflictions between adjacent congestion areas.Experimental results show that the algorithm can considerably reduce routing congestion and preserve the performance of the initial placement with high speed.
A new algorithm W ECOP is presented to effect incremental changes on a standard cell layout automatically.This algorithm deals with cell inserting and cell moving based on rows instead of on cells as most placement algorithms usually do.An integer programming problem is formulated to minimize the adjustment on the initial placement and a heuristic method is presented to search for a shifting path so as to optimize the wirelength.Test of W ECOP on a group of practical test cases shows that the algorithm can successfully accomplish incremental placement with good quality and high speed.
