A bipolar ±40 mV self-starting boost converter with transformer reuse for thermoelectric energy harvesting

This paper presents a converter for boosting the low-voltage output of thermoelectric energy harvesters to power standard CMOS circuits. The converter can start up from a fully de-energized state off a bipolar ±40 mV input and can harvest net positive energy from voltages as low as ±30 mV in steady state. A single transformer is multiplexed between an oscillator that is used during startup and a flyback converter that is used during steady-state operation. During steady-state operation, the converter is automatically shut off if the input power is found to be too low. Simulation results on the converter designed in a 0.35 µm CMOS process demonstrate a peak steady-state conversion efficiency of 68% at an output voltage of 5.5 V and input voltage range between 30 mV and 500 mV in magnitude.