100 mV–1.2 V fully-integrated DC–DC converters for thermal energy harvesting

Two fully-integrated DC/DC converters for energy harvesting applications are presented. The startup-voltages of the converters are, respectively, 140 and 100 mV, the output voltage exceeds 1.2 V, with a power efficiency of about 20%. The architectures for boosting such extremely low voltages are based on an ultra-low-voltage oscillator cross connected to a capacitive converter. The overall circuits do not require any external components and can be fully integrated in a standard complementary metal oxide semiconductor low-voltage technology. The converters have been designed in United Microelectronics Corporation 180 nm process.