Automated module assignment in stacked-Vdd designs for high-efficiency power delivery

With aggressive reductions in feature sizes and the integration of multiple functionalities on the same die, bottlenecks due to I/O pin limitations have become a critical issue in today's VLSI designs, especially for 3D IC technologies. To alleviate the pin limitation problem, a stacked-Vdd circuit paradigm has recently been proposed in the literature. However, for a circuit designed using this paradigm, a significant amount of power may be wasted if modules are not carefully assigned to different Vdd domains. In this article, we present a partition-based algorithm for efficiently assigning modules at the floorplanning level, so as to reuse currents between Vdd domains and minimize the power wasted during the operation of the circuit. Experimental results on both 3D and 2D ICs show that compared with assigning modules to different Vdd domains using enumeration and simulated annealing, our algorithm can generate circuits with competitive power and IR noise performance, while being orders of magnitude faster.