Energy source lifetime optimization for a digital system through power management

We examine the energy consumption of a digital circuit with voltage scaling and observe its impact on the energy efficiency of the battery. We study the system with a power source under throughput constraints and we propose a method to find a right size of battery to satisfy given system requirements. For systems with limit on battery weight or volume, we suggest a right circuit voltage operating point. Maximizing battery lifetime, expressed in terms of clock cycles, depends upon a proper choice of the supply voltage and the corresponding clock frequency that the circuit would support. Analysis of various batteries shows that when no system performance requirement is specified, the optimum operating supply voltage can be in the subthreshold range.