Toward PDN resource estimation: A law of general power density

The power distribution network (PDN) is an increasingly significant consumer of on-chip interconnect resources. Thus, PDN estimation is increasingly central to system-level interconnect prediction for modern ICs. PDN design and verification require accurate power estimation and realistic current source distribution across a die. However, at early design stages, detailed placement or switching information is rarely available, so that designers either rely on pessimistic overdesign, which can lead to severe routing congestion, or encounter unexpected voltage noise problems at late design stages, which can lead to costly design iterations. In this work, we seek to identify a general trend for power density. From both empirical and analytical studies on random activity distributions, we propose a power law of activity density, which can potentially enable estimates of power density and voltage noise, as well as of required power distribution network (PDN) resources, in early design stages.