PASSIVE TRANSPONDER FOR AN RFID SYSTEM, AND METHOD OF TRANSMITTING DATA FROM/TO A DATA SOURCE OF SUCH A PASSIVE TRANSPONDER

• US 20110133894A1
• Filed: 12/02/2010
• Published: 06/09/2011
• Est. Priority Date: 12/03/2009
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: VOM BOEGEL, Gerd, HENNIG, Andreas
• Granted Patent: US 8,749,358 B2
• Time in Patent Office: Days
• US Class Current: 340/10.1
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/20 using microwaves or radio frequency waves
• CPC Class Codes: H03J 2200/10 Tuning of a resonator by means of digitally controlled capacitor bank
• CPC Class Codes: H03J 3/20 of single resonant circuit by varying inductance only or capacitance only

Abstract

A passive transponder includes an antenna, an antenna oscillator circuit and a data source. The antenna oscillator circuit is configured to operate at a first resonant frequency or at a second resonant frequency, depending on reception of energy at the transponder or on a data transmission from/to the data source.

Claims

1. A passive transponder for an RFID system, comprising:

an antenna;

an antenna oscillator circuit; and

a data source;

wherein

the antenna oscillator circuit is configured to operate at a first resonant frequency or at a second resonant frequency, depending on a reception of energy at the transponder or on a data transmission from/to the data source.

2. The passive transponder as claimed in claim 1, configured to cause switching from the first resonant frequency to the second resonant frequency once the energy transmitted to the transponder has reached a predetermined level.

3. The passive transponder as claimed in claim 1, wherein the antenna oscillator circuit comprises a capacitive assembly and an inductive assembly, the capacitance value of the capacitive assembly and/or the inductance value of the inductive assembly being variable so as to cause switching from the first resonant frequency to the second resonant frequency.

4. The passive transponder as claimed in claim 3, comprising a controller configured to change the capacitance value of the capacitive assembly or the inductance value of the inductive assembly when a predetermined portion of the energy stored within the antenna oscillator circuit is stored within the inductive assembly or within the capacitive assembly.

5. The passive transponder as claimed in claim 3, wherein the capacitive assembly comprises a plurality of capacitive devices, the controller causing switching between the first and second resonant frequencies in that at least one of the capacitive devices of the capacitive assembly is switched into the antenna oscillator circuit or is disconnected from the antenna oscillator circuit.

6. The passive transponder as claimed in claim 3, wherein the capacitive assembly comprises a variable capacitive device.

7. The passive transponder as claimed in claim 5, wherein the inductive assembly comprises an inductive device of the antenna.

8. The passive transponder as claimed in claim 5, wherein the controller is adapted to effect a change in the capacitance value of the capacitive assembly if a predetermined portion of the energy stored within the antenna oscillator circuit is stored within the inductive assembly.

9. The passive transponder as claimed in claim 1, wherein the controller is adapted to effect switching between the first and second resonant frequencies such that a predetermined transmit pulse sequence is generated in dependence on a symbol to be transmitted.

10. The passive transponder as claimed in claim 1, wherein the data source comprises at least one sensor.

11. The passive transponder as claimed in claim 10, wherein the sensor is configured to detect a physiological parameter of a patient, the transponder being configured to be arranged on the patient'"'"'s skin or inside the patient'"'"'s body.

12. A transponder system comprising:

a passive transponder for an RFID system, comprising;

an antenna;

an antenna oscillator circuit; and

a data source;

wherein

the antenna oscillator circuit is configured to operate at a first resonant frequency or at a second resonant frequency, depending on a reception of energy at the transponder or on a data transmission from/to the data source; and

a reader configured to excite the passive transponder at the first resonant frequency and to receive a transmit signal from the passive transponder at the second resonant frequency.

13. The transponder system as claimed in claim 12, wherein the reader comprises an antenna tunable between the first resonant frequency and the second resonant frequency, or a transmit antenna operating at the first resonant frequency and a receive antenna operating at the second resonant frequency.

14. The transponder system as claimed in claim 12, wherein the reader is configured to determine the transmitted data from the received transmit signal from the passive transponder.

15. A method of transmitting data from/to a data source of a passive transponder within an RFID system, the method comprising:

exciting the passive transponder at a first resonant frequency of an antenna oscillator circuit of the passive transponder; and

in the event of a data transmission, switching the first resonant frequency of the antenna oscillator circuit of the passive transponder to a second resonant frequency so as to transmit a data signal at the second resonant frequency.