Conclusions

Processor systems are widely prevalent in portable devices which demand increasingly higher levels of energy-efficiency. However, processor energy-efficiency has lagged behind custom ASIC’s and DSP chips, such that while the processor carries only a fraction of the computational load, it is a significant, if not dominant, component of the overall system energy consumption. In order to address this problem it is necessary to use a design methodology that incorporates energy consumption as a primary consideration in all stages of the design process, from the software down to the circuit design. A critical component of this methodology is maximizing the degrees of design freedom by taking into account the characteristics of the application. If this is done, it is possible to significantly improve processor energy-efficiency, thereby enabling smaller, more powerful, and longer running portable devices.