Charge-recycling voltage domains for energy-efficient low-voltage operation of digital CMOS circuits

We describe an energy-efficient means to achieve on-chip dc-dc conversion for dynamic energy-performance trade-offs in digital circuits. The approach uses balanced voltage islands running at fractions of the 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 of an active on-chip voltage regulation scheme to provide controlled dc-dc conversion with this technique.