A Symmetric Boost Converter with 6 mV Input Voltage and 66% Peak Efficiency for Thermoelectric Energy Harvesting

This work presents the design, simulation, and experimental validation of an ultra-low input voltage symmetric boost converter tailored for thermoelectric energy harvesting in energy-autonomous wireless sensor nodes. The proposed DC-DC architecture combines a Meissner oscillator with a forward converter stage, extending cold-start capability and sustaining high efficiency across a broad input range. The circuit operates without any auxiliary supply and is fully powered from its input voltage. A custom micro-transformer was developed and optimized through PSpice simulations, ensuring reliable operation under the constrained power conditions typical of thermoelectric generators. Within the practical input range of 20-50 mV, the converter delivers 1.33 mW and 7.18 mW output power, achieving a peak efficiency of 66.9% at 20 mV input with 5.5 V output. Efficiency remains consistently above 63.9% across the tested input range. Cold-start operation is demonstrated from 18 mV, delivering 17.95 µW, while stable post-startup operation is sustained down to 6 mV with a regulated 2.12 V output. These results establish the converter as a viable solution for harvesting energy from the minute thermal gradients available in real-world environments, thereby enabling long-term, maintenance-free wireless sensor operation.