RFID TRANSPONDER

• US 20080030307A1
• Filed: 03/09/2007
• Published: 02/07/2008
• Est. Priority Date: 08/03/2006
• Status: Abandoned Application

• Current Assignee: Holtek Semiconductor Incorporated
• Original Assignee: Holtek Semiconductor Incorporated
• Inventors: Chen, Chi-Bing
• Application Number:
  US11/684,390
• Publication Number:
  US 20080030307A1
• Time in Patent Office: Days
• US Class Current: 340/10.34
• CPC Class Codes: G06K 19/0701 at least one of the integrated circuit chips comprising an arrangement for power management
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs

Abstract

A radio frequency identification (RFID) transponder is provided. The RFID transponder includes an LC resonant circuit having a first high frequency (HF) terminal and a second HF terminal, producing an AC signal, and transmitting a data; a full-wave rectifying circuit having a high voltage terminal, a low voltage terminal, a first terminal electrically connected to the first HF terminal, and a second terminal electrically connected to the second HF terminal, and rectifying the AC signal to a DC signal; and a first data modulating circuit having a third and a fourth terminals respectively electrically connected to the low voltage terminal and the second HF terminal, wherein the first data modulating circuit is coupled to a part of the full-wave rectifying circuit so that the transponder respectively transmits the data and is charged when the AC signal is respectively a negative AC signal and a positive AC signal.

Claims

1. A radio frequency identification (RFID) transponder, comprising:

an LC resonant circuit having a first high frequency (HF) terminal and a second HF terminal, producing an AC signal, and transmitting a data;

a full-wave rectifying circuit having a high voltage terminal, a low voltage terminal, a first terminal electrically connected to the first HF terminal, and a second terminal electrically connected to the second HF terminal, and rectifying the AC signal to a DC signal; and

a first data modulating circuit having a third and a fourth terminals respectively electrically connected to the low voltage terminal and the second HF terminal,

wherein the first data modulating circuit is coupled to a part of the full-wave rectifying circuit so that the transponder respectively transmits the data and is charged when the AC signal is respectively a negative AC signal and a positive AC signal.

2. A transponder as claimed in claim 1, further having a first inductor and a first capacitor parallel to each other between the first HF terminal and the second HF terminal.

3. A transponder as claimed in claim 1, wherein the full-wave rectifying circuit is a bridge rectifying circuit including a diode.

4. A transponder as claimed in claim 1, wherein the low voltage terminal is grounded, the negative AC signal is in a negative half cycle, and the positive AC signal is in a positive half cycle.

5. A transponder as claimed in claim 1, further cooperating with an interrogator, wherein the LC resonant circuit further comprises a first inductor, the interrogator comprises a second inductor, and the AC signal is generated when the second inductor approaches the transponder.

6. A transponder as claimed in claim 1, further comprising:

an electric charge storage capacitor electrically connected to the high voltage terminal and the low voltage terminal and storing electric charges of the DC signal;

an over-voltage protecting circuit parallel to the electric charge storage capacitor for protecting the transponder;

a data storage device parallel to the over-voltage protecting circuit for storing the data; and

a digital controlling circuit coupled to the data storage device and the first data modulating circuit for determining an address for the data.

7. A transponder as claimed in claim 6, wherein the first data modulating circuit is a first transistor switch further having a first controlling terminal, and the first controlling terminal is electrically connected to the digital controlling circuit.

8. A transponder as claimed in claim 7, further comprising a second data modulating circuit having a fifth and a sixth terminals, wherein the fifth and the sixth terminals are respectively electrically connected to the first HF terminal and the low voltage terminal.

9. A transponder as claimed in claim 8, wherein the second data modulating circuit assists an operation of the first data modulating circuit and includes a second transistor switch further having a second controlling terminal, and the second controlling terminal is electrically connected to the digital controlling circuit and controls the second data modulating circuit.

10. A transponder as claimed in claim 7 further comprising a second data modulating circuit coupled between the low voltage terminal and the third terminal for assisting an operation of the first data modulating circuit.

11. A transponder as claimed in claim 10, wherein the second data modulating circuit is one selected from an inductor and a capacitor.

12. An RFID transponder, comprising:

an LC resonant circuit having a HF terminal and providing an AC signal;

a rectifying circuit comprising a low voltage terminal and rectifying the AC signal to a DC signal; and

a first data modulating circuit having two ends respectively electrically connected to the low voltage and the HF terminals,

wherein the transponder respectively transmits a data and is charged when the AC signal is respectively a negative AC signal and a positive AC signal.

13. A transponder as claimed in claim 12, wherein the rectifying circuit is a full-wave rectifying circuit.

14. An RFID transponder, comprising:

an LC resonant circuit having a first high frequency (HF) terminal and a second HF terminal, producing an AC signal, and transmitting a data;

a full-wave rectifying circuit having a high voltage terminal, a low voltage terminal, a first terminal electrically connected to the first HF terminal, and a second terminal electrically connected to the second HF terminal, and rectifying the AC signal to a DC signal;

a first data modulating circuit having a third and a fourth terminals respectively electrically connected to the low voltage terminal and the second HF terminal;

an electric charge storage capacitor electrically connected to the high voltage terminal and the low voltage terminal and storing electric charges of the DC signal;

an over-voltage protecting circuit parallel to the electric charge storage capacitor for protecting the transponder;

a data storage device parallel to the over-voltage protecting circuit for storing the data; and

a digital controlling circuit coupled to the data storage device and the first data modulating circuit for determining an address for the data.

15. A transponder as claimed in claim 14, wherein the full-wave rectifying circuit is a bridge rectifying circuit including a diode.

16. A transponder as claimed in claim 14, wherein the low voltage terminal is grounded, the negative AC signal is in a negative half cycle, and the positive AC signal is in a positive half cycle.

17. A transponder as claimed in claim 14, further cooperating with an interrogator, wherein the LC resonant circuit further comprises a first inductor, the interrogator comprises a second inductor and the AC signal is generated when the second inductor approaches the transponder.

18. A transponder as claimed in claim 14, wherein the first data modulating circuit is a first transistor switch further having a first controlling terminal, and the first controlling terminal is electrically connected to the digital controlling circuit.

19. A transponder as claimed in claim 18, further comprising a second data modulating circuit having a fifth and a sixth terminals, wherein the fifth and the sixth terminals are respectively electrically connected to the first HF terminal and the low voltage terminal.

20. A transponder as claimed in claim 19, wherein the second data modulating circuit assists an operation of the first data modulating circuit and includes a second transistor switch further having a second controlling terminal, and the second controlling terminal is electrically connected to the digital controlling circuit and controls the second data modulating circuit.

21. A transponder as claimed in claim 18 further comprising a second data modulating circuit coupled between the low voltage terminal and the third terminal for assisting an operation of the first data modulating circuit.

22. A transponder as claimed in claim 21, wherein the second data modulating circuit is one selected from an inductor and a capacitor.