Wi-fi Energy Harvester for Low Power Rfid Application

In recent years, active Radio Frequency Identification (RFID) tags have crossed into ultra low power domain. With obvious advantages over passive tags, a setback for active tag growth is the need for battery replacement and limited operational life. Battery life could be extended by scavenging surrounding Wi-Fi signals using rectenna architecture which consists of a receiving antenna attached to a rectifying circuit. A seven stage Cockroft-Walton voltage multiplier optimized for low input power (below 0 dBm) is proposed. Prototype was fabricated on RT/Duroid 5880 (RO5880) printed circuit board (PCB) substrate with dielectric constant and loss tangent of 2.2 and 0.0009 respectively. Experimental results show that 2 V output voltage can be harvested from an operating frequency of 2.48 GHz with −9 dBm (0.13 mW) sensitivity with 1.57 mm board thickness.