Selecting Impedance States in a Passive Computational RFID Tag Backscattering in PSK

A methodology to carefully select the impedance states of a backscatter phase-shift keying (PSK) load modulator in a passive computational ultrahigh-frequency (UHF) radio frequency identification (RFID) tag is presented. Considering the most significant tag read range limitations reader sensitivity, power transmission and bit error rate (BER), the proposed selection results in constant power transmission to the energy harvester and thus in an increase of the average power at the input of the energy harvester during tag-to-reader communication. A graphical tool to select the modulator impedance states using a Smith chart is proposed.