Power Sub-Mesh Construction in Multiple Power Domain Design with IR Drop and Routability Optimization

Multiple power domain design is prevalent for achieving aggressive power savings. In such design, power delivery to cross-domain cells poses a tough challenge at advanced technology nodes because of the stringent IR drop constraint and the routing resource competition between the secondary power routing and regular signal routing. Nevertheless, this challenge was rarely mentioned and studied in recent literature. Therefore, in this paper, we explore power sub-mesh construction to mitigate the IR drop issue for cross-domain cells and minimize its routing overhead. With the aid of physical, power, and timing related features, we train one IR drop prediction model and one design rule violation prediction model under power sub-meshes of various densities. The trained models effectively guide sub-mesh construction for cross-domain cells to budget the routing resource usage on secondary power routing and signal routing. Our experiments are conducted on industrial mobile designs manufactured by a 6nm process. Experimental results show that IR drop of cross-domain cells, the routing resource usage, and timing QoR are promising after our proposed methodology is applied.