A Wide Conversion Ratio, Extended Input 3.5-μA Boost Regulator With 82% Efficiency for Low-Voltage Energy Harvesting

An inductive boost regulator is presented that can harvest energy over a wide input voltage range. The wide input range is enabled by a current-based analog oscillator capable of providing very high duty cycle. The analog control circuits are designed to operate at subthreshold voltage to enable low voltage all electronic autonomous startup. A test chip designed in 130-nm CMOS demonstrates energy harvesting from as low as 12-mV input while biased by an external 1-V battery and autonomous (without using any additional device or battery) startup above 305 mV at output. The design typically consumes 3.5-μA standby current, achieves peak efficiency of 82%, and can regulate output from 0.66 to 3.3 V. The booster is coupled with a thermoelectric generator and the integrated system delivers output power of 6 μW at ~2 °C temperature difference to a maximum of 12 mW at ~50 °C temperature difference.