Multi-Objective 3D Floorplanning with Integrated Voltage Assignment

Abstract

Voltage assignment is a well-known technique for circuit design, which has been applied successfully to reduce power consumption in classical 2D integrated circuits (ICs). Its usage in the context of 3D ICs has not been fully explored yet although reducing power in 3D designs is of crucial importance, for example, to tackle the ever-present challenge of thermal management. In this article, we investigate the effective and efficient partitioning of 3D designs into multiple voltage domains during the floorplanning step of physical design. In particular, we introduce, implement, and evaluate novel algorithms for effective integration of voltage assignment into the inner floorplanning loops. Our algorithms are compatible not only with the traditional objectives of 2D floorplanning but also with the additional objectives and constraints of 3D designs, including the planning of through-silicon vias (TSVs) and the thermal management of stacked dies. We test our 3D floorplanner extensively on the GSRC benchmarks as well as on an augmented version of the IBM-HB+ benchmarks. The 3D floorplans are shown to achieve effective trade-offs for power and delays throughout different configurations—our results surpass naïve low-power and high-performance voltage assignment by 17% and 10%, on average. Finally, we release our 3D floorplanning framework as open-source code.