Dual Field Communication Scheme for UHF (860–960 MHz) Gen2 RFID Chip

Abstract

The proposed UHF Gen2 RFID chip expands its applications to both FFC and NFC through dual field communication scheme with the dual antenna ports. An RF front end circuit with dual field communication antenna ports and the embedded FeRAM technology on the passive UHF Gen2 RFID chip enables the excellent operating performances and the low cost chip for the tag chip applications from the item level to pallet. The metal-ferroelectric-metal (MFM) capacitor, which is the replacement capacitor device for metal-insulator-metal (MIM) or poly-insulator-poly (PIP), is composed of the ferroelectric material as a dielectric insulator. The MFM capacitor is made simultaneously during the FeRAM memory cell process integration without any additional process integration cost. The MFM capacitor of PZT with the thickness of 0.15μm has the high capacitance value of 20–40 fF at unit μm2 area size. The MFM can be stacked over the CMOS layout area, which saves dramatically the capacitor layout area. The MFM capacitor also has the high breakdown voltage at the thickness of 0.15 μm, which enhances the reliability in the surging electrostatic discharge (ESD) current into the dual antenna ports. The pumping capacitors of the multi-stage voltage pump are composed of the multiple MFM capacitors of the capacitance value of the element device of 1–2 pF. The reservoir capacitors of the VDD power line also are composed of the MFM capacitors with the total capacitance value of 500–1000 pF. The rectification diode device is composed of the near zero threshold voltage NMOS (ZNMOS) transistor with a threshold voltage level of 0.1–0.2 V.