Automated environment aware nW FOCV — MPPT controller for self-powered IoT applications

This paper presents, a complete energy harvesting system with improved implementation of Fractional Open Circuit Voltage (FOCV) technique, to mitigate obligation of using off chip sampling capacitor, gratuitous periodic open circuit operation for Maximum Power Point Extraction (MPP) from solar cell. A possible solution to minimize the reverse current in solar cell due to abrupt decline in irradiance is also proposed. Thus, usual off-chip sampling capacitance can be effectively replaced by on-chip capacitance as low as 3.75pF. Entire system is implemented in 180nm CMOS technology and the proposed blocks consumes 0.675mm × 0.425mm area and an average power of 340nW.