An Integer Linear Programming Algorithm for Crosstalk-Constrained River Routing

As advances in technology produce smaller interconnection wire spacing and higher circuit operating frequency, the effect of crosstalks on performance and even on yield in integrated circuit design and manufacturing thus increases rapidly. Consequently, reduction of crosstalks between interconnection wires has become important in VLSI (very large scale integration) design. In this paper, an approach for the gridded river routing problem with the objective of minimizing crosstalks is presented. Given an initial routing solution generated by a conventional river routing algorithm, the reduction of crosstalks is carried out by an iterative reassignment of the horizontal and vertical wire segments. To effectively and optimally perform the reassignment process, an integer linear programming (ILP) formulation is proposed in conjunction with procedures for reducing the number of variables and constraints. The experimental results show that the proposed ILP approach is very promising. On an average, this approach shows a 20% increment for total slack when comparing the initial solutions; moreover, all the crosstalk constraints are satisfied with some margins for each test example.