A 580 nW Dual-Input Energy Harvester IC Using Multi-Task MPPT and a Current Boost Converter for Heterogeneous Source Combining

Herein, we present a multi-energy harvesting interface integrated circuit (IC) that enables the efficient combination of heterogeneous power sources. An electromagnetic vibration energy generator (EVG) and a thermoelectric energy generator (TEG) are the two energy sources, which have quite different internal resistance (tens and kilo-Ohms). To solve the challenge of combining heterogeneous sources, we propose a current boost converter (CBC), which achieves the resistance transformation as well as the source type conversion. The challenge of realizing maximum power point tracking (MPPT) for each source is tackled by using a multi-task MPPT controller, which is efficiently shared between the two sources. To achieve energy harvesting under uncertain and random source conditions, we propose an input (VIN)-dependent clock generator (VCG) and a vibration pulse detector (VPD). The VCG tracks the change of source conditions to generate the clock for the MPPT controller. The VPD allows tracking of the random amplitude and frequency changes of the EVG. The energy harvester is fabricated in a 0.18 μ m process with a thick top-metal option. Measured results show successful source detection, switching, and MPPT operation. The proposed IC provides an output power of up to 119 μ W with an end-to-end peak efficiency of 82% by consuming 582 nW.