A 0.48mm2 5μW-10mW indoor/outdoor PV energy-harvesting management unit in a 65nm SoC based on a single bidirectional multi-gain/multi-mode switched-cap converter with supercap storage

We propose an energy-harvesting management unit to interface a PV harvester with a storage supercapacitor while generating a 1V regulated supply V_REG. Direct connection between stacked PV cells and V_REG allows virtual 100% conversion efficiency between the harvester and the supplied circuits, while the use of a single bidirectional switched-capacitor DC/DC converter between V_REG and the supercap allows 0.48mm² area in a 65nm IoT vision SoC with a single external filtering capacitor. To cope with the 0-3V charge-dependent supercap voltage range and the wide 5μW-10mW harvester/load power range, the converter features adaptive selection between multiple voltage gains and power modes.