Enhanced Two-Way Communication for Battery-Free Wireless Sensors: SWIPT with IM3 Backscattering

This paper presents a combined multi-tone simultaneous wireless information and power transfer (SWIPT)/third-order intermodulation (IM3) backscattering architecture. This integrated system uses the diode's nonlinear behaviour as well as frequency division duplex (FDD) to perform three critical functions: downlink communication, uplink communication, and energy harvesting. Measurements of the prototype design prove that the downlink and uplink communication does not affect the wireless power transfer. A downlink data rate of 1 kbps, 4.84 dB IM3 backscattering dynamic range, and 30% power conversion efficiency demonstrated when the tag is fed with 100
$\mu W$
RF power.