Design and Analysis of Harmonic Tag with RF Energy Harvesting Circuit

Abstract

In this paper, the design and analysis of a harmonic tag with an RF energy harvesting circuit is performed. In the first research stage, a low power passive harmonic tag has been designed at 2.45/4.9 GHz whose main function is to receive the fundamental signal and transmit harmonics. In the second stage, an RF energy harvesting circuit is designed at 2.45 GHz by using voltage doubler RF rectifier. Additionally, a diplexer was inserted between the harmonic tag and the RF energy harvesting circuit to separate the fundamental signal from the second harmonic. Impedance matching is performed between the antennas and the harmonic tag, as well as between the harmonic tag and the RF rectifier, with aim to obtain maximum power transfer. Results accomplished by ADS simulations for different input power levels provide a performance evaluation of the harmonic tag and the RF energy harvesting circuit in terms of RF-DC conversion efficiency, DC power, and second harmonic power. For the observed input power levels (-20 dBm to 10 dBm), the gained RF-DC conversion efficiency varies between 7 % and 17 %, the output DC voltage varies between 0.1 V and 3.6 V, while the second harmonic power goes from -61 dBm to -3 dBm.