Timing-driven detailed placement for standard-cells based on lookup-table delay model

摘要

This paper presents a timing-driven detailed placement algorithm for standard-cell VLSIs based on a new lookup-table delay model. The new model can give more accurate delay estimation. We use local optimization in detailed placement and a net weighting method to cope with timing constraints. Timing verifications are carried out after each optimization iteration and net weights are adapted dynamically. We present 4 methods to modify net weights and study the combination effect of these methods. Experimental results show that our net-weighting method can reduce the maximum delay up to 15 percent compared to nontiming-driven placement, with little loss in the total wire length.