An ultra-low power voltage regulator system topology for wireless sensor networks powered by energy harvesting has been studied. The sensor node state information is utilized to reduce the quiescent current and power consumption of the regulator system. The chip has been fabricated using an ON Semiconductor 0.5 mu m process. The system was shown to provide a stable 1.8 V output voltage to the load when the supply voltage changes. At a supply voltage of 2 V, the power consumption of the system is only 0.44 mu W when a 1% duty cycle is employed. (C) 2014 Elsevier Ltd. All rights reserved.