A Self-Adaptive Time-Based MPPT With 96.2% Tracking Efficiency and a Wide Tracking Range of 10 μA to 1 mA for IoT Applications

This paper presents a novel ultra-low power maximum power point tracking (MPPT) technique with a wide tracking range. An indirect, non-interrupting approach using a novel timing-based algorithm is proposed. The proposed MPPT technique is self-adaptive and applicable to the various types of photovoltaic cells without external reconfiguration or the change of passive components. In addition, a variable gain is employed in the one-hot barrel shift register to reduce the transient response time. A test chip was fabricated in 65-nm CMOS technology. The test chip can harvest energy with the input voltage range of 0.4 V to 1.7 V and the step response time of less than 100 ms at the minimum supply voltage of 0.8 V. The tracking efficiency is up to 96.2% when supplied by a photovoltaic micro-cell array using an irradiation range of 200 lux to 1000 lux.