Single-Inductor-Multiple-Tier Regulation: TSV-Inductor-Based On-Chip Buck Converters for 3-D IC Power Delivery

On-chip inductive buck converters gain popularity due to their higher efficiency at higher load currents compared to its linear and capacitive counterparts. Through-silicon-via inductors (TSV-Inductors) in 3-D integrated circuit (3-D IC) technology can be used for the buck converter implementation that reduces the metal resource consumption of the inductor. However, in 3-D ICs, the regulated voltage from buck converters might be required for multiple tiers. Simply designing one buck converter per tier is apparently resource consuming. This paper fully utilizes the feature of TSV-Inductor and temporal/spatial sharing techniques to enable single-inductor-multiple-tier regulation for 3-D ICs. Experimental results suggest that under the same design specifications and resource consumption, the TSV-Inductor-based time multiplexing buck converter (TMBC) and the shared inductor buck converter (SIBC) help increase the efficiency by up to 15% and 25%, respectively, compared with the conventional power delivery scheme using one TSV-Inductor-based buck converter per tier. Moreover, the ripples of the TSV-Inductor-based TMBC and SIBC can be reduced by up to 3x and 6x, respectively. To the best of our knowledge, this is the very first work exploring buck converter sharing between multiple tiers in 3-D ICs.