A Power Management Unit for Battery-Less TEG Energy Harvesting With Low Voltage Self-Startup

A battery-less thermoelectric energy harvesting power management integrated circuit (PMIC) with low self startup voltage is implemented in a 180 nm CMOS process. A two stage step-by-step self-startup circuit enables operation the system from input voltages as low as 10 mV. A maximum power point tracking (MPPT) circuit with a frequency trimming technique is employed to extract the maximum energy from the TEG under a smaller temperature gradient and improve the overall stability of the system. Zero-current sensing (ZCS) detects the position of zero current during the discharge of the inductor and ends the discharge process in time by using two comparator monitoring methods, greatly reducing the energy backflow at the load side and improving the conversion efficiency. With a minimum cold-start voltage of180 mV and a minimum operating voltage of10 mV, the average power consumption of the PMIC was 24.6 $\mu$W, the output voltage range was 1.7 V, and the end-to-end conversion efficiency of the boost converter was 78.3%.