Abstract: The present invention discloses a radio frequency identification device implemented with a metal-gate semiconductor fabrication process, wherein the charge capacitor, which is formed by the special parasitic N-type and P-type guard rings in the chip fabricated with the metal-gate process, incorporated with the original P-type and N-type transistors of metal oxide semiconductor (PMOS/NMOS) not only can provide a horizontal surface current but also can provide a rectified current for the performance of the entire circuit, which can advance the metal gate process to RFID industry in cooperation with an identification code holder circuit and a non-synchronous local oscillation circuit so that the fabrication cost can be lowered and the fabrication time can be shortened.