A Battery-Less Energy Harvesting Front-End for Powering Multiple IoT Nodes Using Single Solar Cell: A System-Level Perspective

This paper presents system-level considerations for developing a battery-less photovoltaic energy harvesting frontend for powering multiple self-sustainable IoT nodes using a single solar cell. The system architecture includes a maximum power point tracking (MPPT) converter in the first stage, followed by a single-inductor multiple-output (SIMO) converter in the second stage. The instantaneous high power requirements of the IoT nodes under active operation for a short duration are fulfilled by a super-capacitor as a storage element replacing the use of environmentally hazardous batteries. Two SIMO converter topologies are developed to cater for the diverse requirements of IoT nodes: Topology-I, i.e., the buck-boost derived SIMO converter, and Topology-II, i.e., the buck-derived SIMO converter. The complete battery-less energy harvesting front-end is implemented in a single chip using 180-nm CMOS technology. The efficacy and energy-autonomy operations of the overall system are demonstrated in the measured results. The first stage maximizes the power extraction from the solar harvester and the second stage delivers power to the multiple IoT nodes along with the cold-start and the over-voltage protection for a reliable and self-sustainable operation of the overall system.