Energy-efficient low-voltage operation of digital CMOS circuits through charge-recycling

This paper describes an energy-efficient means to achieve on-chip dc-dc conversion for digital CMOS circuits. The approach uses balanced voltage islands running at fractions of the off-chip supply voltage. Charge "discarded" by one domain is "recycled" to supply energy for another. When the domains are ideally balanced, all the energy dissipated by electrons in "dropping" to lower potentials is used for active computation. We describe the design and measurement of a prototype system in a 0.18 mum CMOS process that provides active on-chip voltage regulation and controlled dc-dc conversion with this technique.