Optimum ASK Modulation Scheme for Passive RFID Tags Under Antenna Mismatch Conditions

We propose optimized ON/OFF states of the backscattered amplitude shift keying (ASK) modulator for the passive RF identification (RFID) tags. This takes into account both the reader receiver sensitivity and tag antenna mismatch conditions. Based on the analysis of the power transfer between the passive RFID tag and reader, we derived the optimum configuration of the ASK modulator. It maximizes the harvestable power to enhance the identification range between the tag and reader. The performance of the proposed modulator configuration was superior to the conventional scheme. We also developed an optimization procedure of the modulator for a given receiver sensitivity of the reader and various antenna mismatch conditions of the tag.