Design of a nano-power fully autonomous multi-source energy harvesting circuit

This paper presents a nano-power fully autonomous multi-source energy harvesting circuit for solar, thermal, and vibration energy. A low-power active rectifier is employed to improve vibration energy extraction efficiency. A maximum power point tracking circuit based on a fractional open-circuit voltage technique is applied to solar and thermal channels. A passive self-starting technique makes the harvester autonomous and performs a battery-less start-up from a fully discharged state. An asynchronous logic is adopted for the control unit to reduce intrinsic power consumption. Simulation results show that, as low as 100nA quiescent current in all is drawn by the converter and a peak conversion efficiency of 83.6% is achieved. There are only four external components: two capacitors for DC sources, a single inductor and an external capacitor for energy storage.