CLOAKING CIRCUIT FOR USE IN RADIO FREQUENCY IDENTIFICATION TAGS AND METHOD OF CLOAKING RFID TAGS TO INCREASE INTERROGATION RELIABILITY

摘要

The antenna of an RFID tag (100) is disconnected from the balance of the RFID chip by means of a series switch (24) activated in response to a logic command, CLOAK. Activation of the switch (24) disconnects the antenna (16) of the RFID tag for the remainder of the chip and effects a high impedance resistance across the antenna terminals (12, 14). An RC circuit (36, 38) is charged by activation of the CLOAK signal and thereafter discharges during a predetermined time period as determined by a high impedance series antifuse leakage transistor (34). The antenna is thus disconnected for a time sufficient to allow the remaining RFID tags to be identified.