A 0.21-V minimum input, 73.6% maximum efficiency, fully integrated voltage boost converter with MPPT for low-voltage energy harvesters

This paper proposes a fully integrated voltage boost converter with a maximum power point tracking (MPPT) circuit for ultra-low power energy harvesting. The converter is based on a conventional charge pump circuit and can deliver a wide range of load current by using nMOS and pMOS driver circuits for highly efficient switching operation. The MPPT circuit we propose dissipates nano-watt power to extract maximum power regardless of the harvester's power generation conditions and load current. The measurement results demonstrated that the circuit converted a 0.49-V input to a 1.46-V output with 73.6% power conversion efficiency when the output power was 348 μW. The circuit can operate at an extremely low input of 0.21 V.