An Inductorless DC–DC Converter for Energy Harvesting With a 1.2- $\mu\hbox {W}$ Bandgap-Referenced Output Controller

We present a fully integrated dc-dc converter for micropower energy harvesting. A 1.2- μW bandgap-referenced output controller provides output regulation at 1.4 V, achieving quiescent power of 3 μW and a maximum overall efficiency of 58% at 11 μW output power. A modified four-phase charge pump provides a 3× voltage boost and a minimum input voltage of 270 mV in free-running mode. Using dual switches driven from both the converter input and output, the chip achieves boost without external excitation or external components.