A fully batteryless multiinput single inductor single output energy harvesting architecture

Abstract

Conventional energy architectures that utilize multiple ambient energy sources are initiated either by an external power supply or through the addition of an extra power source (e.g., battery) to the architecture. However, these interventions compromise the goal of a self-sustainable energy harvesting system. Moreover, conventional architectures are not effective in situations where space is limited (e.g., an artificial heart) or when access to this space is difficult (e.g., human implantable devices), due to their large battery size. Thus, conventional energy combiner circuits that use multiple energy sources are not well suited for supplying power to most applications. This paper presents a fully batteryless energy combiner architecture with a single inductor for the use of multiple ambient energy sources, including a solar cell and a microbial fuel cell. For each energy source, an auxiliary circuit (i.e. a charge pump) is implemented in order to provide a power supply to a digital control circuit, which consecutively connects each ambient energy source to a power converter. This novel architecture is completely self-starting and requires no additional extra power source or battery. This architecture has been designed and verified using a 0.13-$\mu$m CMOS process and a peak end-to-end efficiency of 79.33% for two ambient sources is achieved. This proposed system is applicable to numerous loads utilized in energy harvesting systems.