RF devices

• US 20090278690A1
• Filed: 05/12/2008
• Published: 11/12/2009
• Est. Priority Date: 05/12/2008
• Status: Active Grant

• Current Assignee: Murata Electronics North America Incorporated (Murata Manufacturing Co Limited)
• Original Assignee: Sychip Incorporated (Murata Manufacturing Co Limited)
• Inventors: Degani, Yinon
• Granted Patent: US 8,102,021 B2
• Time in Patent Office: Days
• US Class Current: 340/572.700
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: G06K 19/07756 the connection being non-galvanic, e.g. capacitive
• CPC Class Codes: G06K 19/07775 the antenna being on-chip
• CPC Class Codes: G06K 19/07779 the inductive antenna being a coil

Abstract

A low cost passive RFID tag uses capacitive or inductive coupling between the RF IC chip and the antenna. Coupling elements are formed directly on the surface of the RF IC chip.

Claims

1. RFID tag comprising:

a) a substrate,

b) an antenna formed on the substrate,

c) an RF IC chip bonded to the substrate and the antenna, the RF IC chip comprising at least one coupling capacitor plate formed on the surface of the RF IC chip so as to electrically couple RF signals between the RF IC chip and the antenna.

2. The RFID tag of claim 1 wherein the antenna comprises at least one antenna capacitor plate and the coupling capacitor plate on the surface of the RF IC chip overlies the antenna capacitor plate.

3. The RFID tag of claim 2 including a dielectric layer formed between the coupling capacitor plate on the surface of the RF IC chip and the antenna capacitor plate.

4. The RFID tag of claim 1 wherein the RF IC chip has two coupling capacitor plates formed on the surface of the RF IC chip, and the antenna has two antenna capacitor plates, with the coupling capacitor plates overlying the antenna capacitor plates.

5. The RFID tag of claim 1 wherein the antenna sections are serpentined metal patterns.

6. The RFID tag of claim 1 wherein the RF IC chip has a surface passivating layer, and the coupling capacitor plate is formed on the surface passivating layer.

7. The RFID tag of claim 6 wherein the coupling capacitor plate on the surface passivating layer is connected to the RF IC chip through a via in the passivating layer.

8. The RFID tag of claim 7 wherein the width of the coupling capacitor plate is greater than twice the width of the via.

9. The RFID tag of claim 1 wherein the substrate comprises paper or plastic.

10. The RFID tag of claim 1 further including at least one supplemental capacitor plate between the RF IC chip and the coupling capacitor plate.

11. RFID tag comprising:

a) a substrate,

b) an antenna formed on the substrate,

c) an RF IC chip bonded to the substrate and the antenna, the RF IC chip comprising at least one inductor element formed on the surface of the RF IC chip so as to electrically couple RF signals between the RF IC chip and the antenna.

12. The RFID tag of claim 11 wherein the antenna comprises at least one antenna inductor element and the inductor element on the surface of the RF IC chip overlies the antenna inductor element.

13. The RFID tag of claim 12 including a dielectric layer formed between the inductor element on the surface of the RF IC chip and the antenna inductor element.

14. The RFID tag of claim 13 wherein the RF IC chip comprises two inductor elements formed on the surface of the RF IC chip, and the antenna comprises two antenna inductor elements and the two inductor elements on the RF IC chip overly the two inductor elements.

15. The RFID tag of claim 13 wherein the RF IC chip comprises a capacitor plate and the antenna comprises a capacitor plate and the capacitor plate on the RF IC chip overlies the antenna capacitor plate.

16. The RFID tag of claim 13 wherein the RF IC chip has a surface passivating layer, and the inductor element is formed on the surface passivating layer.

17. The RFID tag of claim 16 wherein the inductor element on the surface passivating layer is connected to the RF IC through a via in the passivating layer.

18. The RFID tag of claim 13 wherein the substrate comprises paper or plastic.