Closed-system capacitive coupling RFID

A capacitively coupled RFID communications system comprising an RFID tag and an RFID reader, wherein the RFID tag comprises

• an integrated circuit (IC), the IC including
• a first RFID tag electrode,
• a second RFID tag electrode,
• power supply circuitry configured to extract power from a first time-varying signal received from the RFID reader via at least one of the first RFID tag electrode and the second RFID tag electrode, and supply the extracted power to circuitry of the RFID tag, and
• data transmission circuitry configured to receive the extracted power from the power supply circuitry, and transmit data to the RFID reader via at least one of the first RFID tag electrode and the second RFID tag electrode;
• and wherein the RFID reader comprises
• a first RFID reader electrode,
• a second RFID reader electrode,
• driver circuitry configured to provide the first time-varying signal to the RFID tag via at least one of the first RFID reader electrode and the second RFID reader electrode;
• and
• data reception circuitry configured to receive the data from the RFID tag via at least one of the first RFID electrode and the second RFID electrode, and extract the data from the data carrying signal, and wherein the first RFID tag electrode is arranged to capacitively couple with the first RIFD reader electrode to form a first capacitor and the second RFID tag electrode is arranged to capacitively couple with the second RFID reader electrode to form a second capacitor when the RFID tag is in a first position relative to the RFID reader.