With the aim of providing designer guidelines for choosing the most suitable solution, according to the given design specifications, in this paper a review of charge pump (CP) topologies for the power management of Internet of Things (IoT) nodes is presented. Power management of IoT nodes represents a challenging task, especially when the output of the energy harvester is in the order of few hundreds of millivolts. In these applications, the power management section can be profitably implemented, exploiting CPs. Indeed, presently, many different CP topologies have been presented in literature. Finally, a data-driven comparison is also provided, allowing for quantitative insight into the state-of-the-art of integrated CPs.

In this article, a fully-integrated switched-capacitor DC-DC converter based on a Dickson charge pump able to work with input voltage levels that force the transistors working in subthreshold region is presented. The proposed topology exploits resistors in the charge transfer switch in order to overcome the limits of conventional solutions when working in the subthreshold regime. Post-layout simulations using a 28-nm FD-SOI technology show that the CP can boost an input voltage as low as 50 mV to a maximum output voltage of 270 mV, keeping a settling time about 25X lower than the conventional dual-branch cross-coupled charge pump and a voltage conversion efficiency higher than 76%. The proposed topology is particularly suited for the start-up of power management units supplied by thermoelectric generators.

This paper aims to review the recent architectures of power management units for ultrasound-based energy harvesting, while focusing on battery-less implantable medical devices. In such systems, energy sustainability is based on piezoelectric devices and a power management circuit, which represents a key building block since it maximizes the power extracted from the piezoelectric devices and delivers it to the other building blocks of the implanted device. Since the power budget is strongly constrained by the dimension of the piezoelectric energy harvester, complexity of topologies have been increased bit by bit in order to achieve improved power efficiency also in difficult operative conditions. With this in mind, the introduced work consists of a comprehensive presentation of the main blocks of a generic power management unit for ultrasound-based energy harvesting and its operative principles, a review of the prior art and a comparative study of the performance achieved by the considered solutions. Finally, design guidelines are provided, allowing the designer to choose the best topology according to the given design specifications and technology adopted.

In this brief a brief tutorial of charge pump topologies for management of self-powered nodes in ultra-low-power applications, such as Internet of Things nodes, is presented. It aims to provide to the designer guidelines to choose the most suitable solution, according to the given design specifications. After a brief historic evolution, the main design equations of charge pumps and a collection of the recent proposed topologies and regulation schemes are discussed, allowing for qualitative insight into the state-of-the-art of integrated topologies.

This paper proposes a comparative study of regulation schemes for charge-pump-based voltage generators using behavioral models in Verilog- Analog Mixed Signal (AMS) code. An accurate and simple model of the charge pump is first introduced. It allows reducing the simulation time of complex electronic systems made up by both analog and digital circuits while maintaining a good agreement with transistor-level simulations. Finally, a comprehensive comparative study of the different regulation schemes for charge pumps is reported which allows the designer to choose the most suitable topology for a given application and Charge Pump (CP) operative zone.