2.4 GHz RF energy harvesting rectifier chip with harmonic backscattering detection capability

In this paper, we design a 2.4 GHz RF energy harvesting rectifier chip which can be identified by a backscattering second-harmonic index signal. For the traditional RF energy harvester, the backscattered harmonic wave is often regarded as a loss part of available energy. Different from the traditional ones, we proposed a rectifier which is with a stronger backscattered harmonic when operated in location detection mode and followed with a better power conversion efficiency (PCE) in energy hunting mode. The energy harvesting rectifier has the maximum PCE up to 72% when the input power is-7.2 dBm and the output load is 10 mathrm{k} Omega. And the peak PCE is 60% with an input power of-19.4 dBm and an output load of 100 mathrm{k} Omega. The rectifier gives a sensitivity of-21.4 dBm for 1 V output voltage with a 10 mathrm{M} Omega probe load. When the input power is +5 dBm, the harvester can provide a 40 dB difference of second harmonic power between the above mentioned different modes for location detection. The effective input power range (IPR) is 14 dB which is defined as the power range limited by the PCE greater than 10% and the input power smaller than-10 dBm. We also newly proposed two figure of merit (FOM) expressions as the evaluation indexes of energy harvesting circuit performances.