An 80 mV Startup Voltage Fully Electrical DC-DC Converter for Flexible Thermoelectric Generators

This paper presents a fully electrical dc-dc converter designed for thermoelectric generator (TEG) for energy harvesting applications. The proposed flexible TEG has been achieved by a screen printing technology on a 80 mu m thick common paper and thin Kapton foil and integrates 280 thermocouples for an output voltage of about 75 mV with 5 K of thermal gradient. In order to step up the voltage at the output of the thin-film flexible TEG, a dc-dc converter has been designed. This latter operates with an input voltage ranging from 80 up to 370 mV. The proposed dc-dc converter achieves an automatic control based on pulsewidth modulation, ensuring 1 V output voltage. The control circuit includes two sections. The first one provides a forward control operating in the 80-150 mV input voltage range. The second one operates a feedback control, as the output voltage of TEG is higher than 150 mV. The dc-dc converter is implemented in a 65 nm CMOS technology, achieving a 73% peak efficiency.