Using Radio Frequency (RF) energy to power ultralow power devices is an appropriate solution to reduce the dependency on batteries for low power consumption connected devices. However, providing a regulated Direct Current (DC) voltage from RF power is a challenging task. This work presents a simple and efficient rectifier which has an RF/DC conversion efficiency of 29 % and outputs a DC voltage of 227 mV from an input RF power of −20 dBm at 848 MHz. This performance is sufficient to operate a commercial Power Management Integrated Circuit which regulates the DC output voltage of the rectifier and outputs a power of 324 nW aiming to power supply an ultralow power consumption Wake-up Radio Receiver. The required RF power, to output a regulated DC voltage, is so far the lowest reported in the literature for an RF harvester designed with offthe-shelf components and using a continuous wave (CW) signal.