A −19dBm sensitivity integrated RF-DC converter with regulated output voltage for powering UHF wireless sensors

This paper presents a -19dBm sensitivity RF-DC converter for energy harvesting applications. It is able to harvest the energy from a dipole antenna operating at 866.5MHz (European UHF RFID frequency) providing a regulated output voltage in the range between 1.9V to 2.4V over a 2MΩ resistive load. Such voltage level is suitable to supply body sensor nodes. The four stages Dickson's RF-DC rectifier converts the UHF RF input signal to a 2V DC output, feeding the following two stages DC-DC Pelliconi's charge pump. The DC-DC charge pump, powered by a 90kHz ring oscillator, is used to further step-up the RF-DC rectifier output voltage and to realize the RF to load isolation. The output voltage regulation is performed by a feedback network made by a hysteresis comparator and a Vt-based voltage reference. The RF-DC converter shows a 38% power conversion efficiency at 0dbm input power level.