The Internet of Things (IoT) has found application in many components of implantable medical devices, wearable smart devices, monitoring systems, etc. The IoT devices are conventionally battery powered, even though, in several low power applications, they can also be powered using energy harvesting technology. Independently of the power sources (if batteries or environment), efficient and robust power converters must be designed to provide the small and distributed energy required by such IoT devices. This review paper will first provide an overview about the power consumption in IoT devices; second, it will discuss the most recent research and advance in the field of fully-integrated or embedded DC/DC converters, starting from high-performance integrated charge pumps or embedded inductive boost converters for specific harvesting sources (temperature, solar, and so on), to novel DC/DC converters for multiple energy sources.

Reducing voltage supply is one of the most effective way to reduce the power consumption, but, on the other hand it is a challenging choice for the analog designers. In this paper, different topologies, well-suited for low voltage and ultra-low voltage supply, are depicted, investigated, designed in the same standard 180 nm technology and compared, highlighting the benefits and the possible applications.

In this Letter, a new dual/multiple‐input non‐isolated boost converter is proposed. It provides a positive boosted output voltage without any additional transformer. It is suitable to interface sources of different current–voltage characteristics to a common load, with a simple topology and a low part count. The topology and the behaviour are similar to the single‐input boost converter; hence, the control strategy can be accomplished easily. It can be used in low‐voltage energy harvesting applications to collect energy from multiple sources. Simulations and experimental results are presented to demonstrate the effectiveness of the proposed topology.

Ultra-low power electronic devices, as by the way of example sensor nodes, can be powered by environmental energy harvesting. Thermo generators, solar cells, inductive generators, or radio frequency antennas provide an extremely low output voltage that must be amplified to generate a suitable power supply. This work presents an autonomous self-starting ultra-low voltage DC-DC converter that starts operations at 9 mV. The circuit is inspired by the classical zero voltage switching pushpull Royer oscillator, suitably modified by using JFETs to operate at low voltages. Thanks to the soft switching of the transistors and to the symmetrical use of the transformer, it can reach high voltage gain, high frequency, and high efficiency. Theoretical and simulation-based optimizations were used to design the converter; the results were experimentally verified with several prototypes.