Cooperative integration of harvesting sections for passive RFID communication

This paper considers the integration of three attractive concepts: Electromagnetic Energy Harvesting (EEH), Radio Frequency Identification (RFID) communication, and exploiting the non-linear characteristic of RF devices. An EEH circuit is integrated with a passive RFID tag profiting from three nonlinear phenomena of rectifying elements: (1) the impedance power dependency, (2) the harmonic production, and (3) the RF waveform dependency. The harmonic signals generated by the rectifier section of a commercial 868 MHz RFID chip, and additionally an external modulated signal at the 2.4 GHz ISM band are harvested by rectifier circuit and are used to supply the RFID chip with additional dc energy in order to increase its sensitivity. A prototype is tested and experimental results show the cooperative effect by maximizing the RF-to-dc conversion efficiency of the EEH section (from 40 % to 64 %) and simultaneously enhancing the sensitivity of the RFID chip by 7.2 dB.