Micro-Energy Harvesting System including a PMU and a Solar Cell on the same Substrate with Cold Start-Up from 2.38 nW and Input Power Range up to 10μW using Continuous MPPT

Ferro Santiago, EstebanBrea Sánchez, Víctor ManuelLópez Martínez, PaulaCabello Ferrer, Diego2019-03-122019-04-192018-10-19Esteban Ferro, Víctor Manuel Brea, Paula López and Diego Cabello (2018) Micro-Energy Harvesting System including a PMU and a Solar Cell on the same Substrate with Cold Start-Up from 2.38 nW and Input Power Range up to 10 W using Continuous MPPT. IEEE TRANSACTIONS ON POWER ELECTRONICS, 63(1), 1-12. Doi: 10.1109/TPEL.2018.28771050885-8993http://hdl.handle.net/10347/18342This paper presents a Power Management Unit (PMU) powered by a 1 mm $^2$ solar cell on the same substrate to rise up the harvested voltage above 1.1 V. The on-chip solar cell and the PMU are fabricated in standard 0.18 μm CMOS technology achieving a form factor of 1.575 mm $^2$ . The PMU is able to start up from a harvested power of 2.38 nW without any external kick off or control signal. The PMU features a continuous and two-dimensional Maximum Power Point Tracking (MPPT) working in open-loop mode to handle a harvested power range from nW to $\mu$ W, by modifying both the charge pump topology and the switching frequency. The MPPT is based on four voltage level detectors that define five working regions depending on the illumination and on a self-tuning reference current for a fine adjustment of the switching frequency. The chip also includes an auxiliary charge pump to generate the voltage level necessary for the control circuit, implemented as a Pelliconi charge pump of 8 stages with NMOS transistors in Pwell as diodes. A Dickson charge pump with transmission gates as switches and with variable gain and capacitance per stage is also designed as the main charge pump. Finally, two relaxation oscillators are implemented to drive both charge pumps. This paper is accompanied by a video file demonstrating the PMU operation by powering an off-chip NAND gateeng© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksEnergy harvestingDC-DC power conversionPMUOn-Chip Solar CellAnalog MPPTMicro-Energy Harvesting System including a PMU and a Solar Cell on the same Substrate with Cold Start-Up from 2.38 nW and Input Power Range up to 10μW using Continuous MPPTjournal article10.1109/TPEL.2018.2877105open access