Early-Stage Power Grid Design

Abstract

Many prior works have discussed the power grid design and optimization in the post-layout stage, when design change is inevitably expensive and difficult. In contrast, during the early stage of a development cycle, designers have more flexibility to improve the design quality. However, there are several fundamental challenges at early-stage when design database is NOT complete, including extraction, modeling and optimization. This paper tackles these fundamental issues of early-stage power grid design. The proposed methods have been silicon-validated on 32nm on-market chips and successfully applied to a 22nm design for its early stage power grid design. The findings from such practices reveal that, for sub-32nm chips, intrinsic on-die capacitance and power gate scheme may have more significant impact than expected on power integrity, and need to be well addressed at early stage.