Linear and Switch-Mode Conversion in 3-D Circuits

A methodology for DC-DC conversion in three-dimensional (3-D) circuits is described in this paper. The proposed approach exploits both linear and switching buck converters with different conversion ranges, thereby increasing power efficiency. By replacing the traditional LC filter within a switching converter with a distributed filter, a significant increase in efficiency is demonstrated. Additionally, the physical structure of the filter simultaneously enables the distribution of high current to the load while filtering the switching signal at the input. Design guidelines and expressions are developed, achieving good agreement with simulations based on the MIT Lincoln Laboratories CMOS/SOI 180-nm 3-D technology. The proposed converter distributes 2.5 A maximum current, achieving conversion from 3.3 V to 2.5 V and 1 V with, respectively, 74% and 44% power efficiency.