Fully integrated start-up at 70 mV of boost converters for thermoelectric energy harvesting

Abstract

This paper presents an inductive DC-DC boost converter for energy harvesting using a thermoelectric generator with a minimum start-up voltage of 70 mV and a regulated output voltage of 1.25 V. With a typical generator resistance of 40 Ω an output power of 17μW can be provided, which translates to an end-to-end efficiency of 58%. The converter employs Schmitt-Trigger logic start-up control circuitry and an ultra-low voltage charge pump using modified Schmitt-Trigger driving circuits optimized for driving capacitive loads. Together with a novel ultra-low leakage power switch and the required control scheme, this enables, to the authors knowledge, the lowest minimum voltage with fully integrated start-up.