Low-voltage cold-start circuit for energy harvesting suitable for indoor sunlight

Abstract

This paper proposes a low-voltage cold-start circuit suitable for indoor sunlight energy harvesting in TSMC 40nm CMOS process. The circuit can work normally when the input voltage is as low as 200mV and is compatible with a wide input power range. Pulse-skipping modulation (PSM) is used to control the circuit’s operation and sleep. The main structure includes a ring oscillator, a two-phase clock drive circuit, a linear charge pump, a low-power voltage reference, and a hysteresis comparator. Compared with other cold-start circuits, the structure proposed in this paper can realize the function of voltage rise without the aid of external machinery or voltage. Simulation results show that when the input voltage is in the range of 200mV to 700mV, the cold-start circuit can stably output 800mV to power the subsequent circuit.