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
$\mu \text{m}$
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.