A Wide-Range Capacitive DC-DC Converter with 2D-MPPT for Soil/Solar Energy Extraction

This paper presents a capacitive DC-DC converter with adaptive DC-DC conversion ratios and maximum power point tracking (MPPT) for soil and solar energy extraction. To overcome the varying input power ranges of the soil/solar energy sources, a two-dimension power tracking loop with time-based current slope detection was employed. The design was fabricated in a 0.18-μm CMOS process, achieving >80% efficiency in a throughput power range of 360μW to 25mW in the soil mode and from 400 μW to l0mW in the solar mode while the peak system efficiency is 89.5%.