A Novel Carrier Suppression Method for RFID

When passive RFID tags are used, RFID readers need to transmit a constant carrier, during uplink communication to provide sufficient operating power to the tag. This high power carrier with its associated noise, limits the receiver sensitivity and, hence, the possible reading range. This letter proposes a new way to cancel the received carrier. The topology, based on a directional coupler and a reflective vector modulator, has a very small area consumption and is very attractive to use with integrated reader ICs. The principle of operation as well as the noise contribution of the circuit itself are discussed.