A Self-Resonant Boost Converter for Solar Energy Harvesting with 97% Tracking Efficiency, 80 mV Self-Startup and Ultra-Wide Range Source Tracking

This paper presents a self-resonant boost converter with an ultrawide range source tracking for solar energy harvesting. The tracking algorithm has been achieved using a self-controlled resonant frequency generator (SRFG) and programmable-delay-controller (PDC). The SRFG defines the switching frequency of the converter by utilizing harmonic oscillations such as over-damping, critical-damping, and under-damping. SRFG and PDC are proposed to harvest solar energy over a 300 × range of source resistance 201500 Ω with a peak tracking efficiency of 97%. The converter was fabricated in a 180 nm CMOS process (Die micrograph) and delivers the maximum 120 μ W output power with an 89 % peak efficiency. Solar energy harvester (SEHs) have been adopted for various low-power applications such as smart buildings, healthcare systems, sensor networks, and Internet of Things (IoT). However, due to low light irradiance, the voltage from a solar cell (VHar) may not be enough for powering an electronic device. In this case, a switched-capacitor-based [1], [2] or an inductive-based [3], [4] DC-DC converters have been used for SEH. However, to realize an efficient SEH, there are three main challenges, 1) a better tracking method which allows a wide range of source condition affected by an irregular incident of light, 2) realizing an efficient DC-DC converter by reducing its own power consumption, 3) low-voltage self-startup technique.