: The accumulation of popular features in portable products such as mobile handsets is driving battery life to unacceptably low levels. Substantial change will not come from incremental improvements in voltage regulator efficiency or battery chemistry, but rather from rethinking the paradigm of power consumption vs power delivery. This work proposes that power supply voltages be dynamically sized to the computational task of the moment and also fully adaptive to variations in process and temperature. Test results reported on an image processor reveal a 25% to 63% reduction in power at the 0.18 micron process node.