An enhanced-range RFID tag using an ambient energy powered reflection amplifier

A great challenge in UHF RFID systems consists of increasing their operating range. In this work, a circuit topology consisting of a reflection amplifier and a passive coupler is proposed to both amplify the input signal to the tag as well as the backscattered signal towards the reader. System analysis is provided to estimate the performance requirements of the proposed circuit. The amplifier is optimized in order to maximize its gain while minimizing its dissipated power, thus allowing for low-power operation by using ambient energy harvesting devices such as solar cells. The circuit is compatible with commercial UHF RFID tags and is implemented using low-cost inkjet printing fabrication. Prototypes of the various circuit components are fabricated and evaluated demonstrating the feasibility of the proposed system. Interesting results are showcased for tag efficiency improvement through such non-conventional front-end designs.