Reinforcement Learning-Based Optimization of Back-side Power Delivery Networks in VLSI Design for IR-drop Reduction

초록

On-chip power planning is a crucial step in chip design. As process nodes advance and the need to supply lower operating voltages without loss becomes vital, the optimal design of the Power Delivery Network (PDN) has become pivotal in VLSI to mitigate IR-drop effectively. To address IR-drop issues in the latest nodes, a back-side power delivery network (BSPDN) has been proposed as an alternative to the conventional frontside PDN. However, BSPDN encounters design issues related to the pitch and resistance of through-silicon vias (TSVs). In addition, BSPDN faces optimization challenges due to the trade-off between rail and grid IR-drop, particularly in the effectiveness of uniform grid design patterns. In this study, we introduce a design framework that utilizes reinforcement learning to identify optimized grid width patterns for individual VLSI designs on the silicon back-side, aiming to reduce IR-drop. We have applied our design approach to various benchmarks and validated its improvement. Our results demonstrate a significant improvement in total IR-drop, with a maximum improvement of up to -19.0% in static analysis and up to -18.8% in dynamic analysis, compared to the conventional uniform BSPDN.

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