I. Introduction
With the emerging Internet of Things (IoT), more and more devices are becoming wearable, intelligent and wireless. Having small, usable devices that can process data, communicate wirelessly and operate for extended periods of time without external power source creates challenges for battery and processor technologies. Improved intelligence in devices often results in increased battery consumption due to the additional required digital logic. Since limitations of the current battery technologies inflict a hard upper bound on device usage time without having an external power source available, low-power and energy-efficient operation is an important requirement for embedded devices.