Electromagnetic transponder with no autonomous power supply

• US 7,573,368 B2
• Filed: 12/20/2005
• Issued: 08/11/2009
• Est. Priority Date: 12/20/2004
• Status: Active Grant

• Current Assignee: Stmicroelectronics France (STMicroelectronics NV)
• Original Assignee: STMicroelectronics SA (STMicroelectronics NV)
• Inventors: Conraux, Jerome
• Primary Examiner(s): Wu; Daniel
• Assistant Examiner(s): GIRMA, FEKADESELASS
• Application Number:
  US11/312,790
• Publication Number:
  US 20060132289A1
• Time in Patent Office: 1,330 Days
• Field of Search: 340 101- 1052, 340/539.1, 3405721-5729, 455/558, 455/41.1, 455/73, 455/78, 455/41.2, 455/82, 455/83, 702/189, 428/166, 329/347
• US Class Current: 340/10.3
• CPC Class Codes: G01S 13/75 using transponders powered from received waves, e.g. using passive transponders , or using passive reflectors
• 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

An electromagnetic transponder comprising: an oscillating circuit; a first rectifying bridge having its A.C. input terminals connected across the oscillating circuit and having its rectified output terminals connected at least to a voltage regulator in charge of providing a supply voltage; and a second rectifying bridge, of dimension smaller than that of the first bridge, having its two A.C. input terminals connected across the oscillating circuit and having at least one output terminal connected to a demodulator of data sensed by the oscillating circuit.

Claims

1. An electromagnetic transponder, comprising:

an oscillating circuit that includes an antenna;

a first rectifying bridge having its A.C. input terminals connected across the oscillating circuit and having its rectified output terminals connected at least to a voltage regulator in charge of providing a supply voltage and further connected to a modulator; and

a second rectifying bridge, of dimension smaller than that of the first bridge, having its two A.C. input terminals connected across the oscillating circuit and having at least one output terminal connected to a demodulator of data sensed by the oscillating circuit.

2. The transponder of claim 1, wherein the surface area ratios of the first and second rectifying bridges to the total surface area taken up by the bridges formed in integrated form range between 80-20 and 98-2, preferably between 93-7 and 97-3.

3. The transponder of claim 1, wherein a bandpass filter is interposed between the second rectifying bridge and the demodulator.

4. The transponder of claim 1, wherein a low-pass filter is interposed between the first rectifying bridge and the voltage regulator.

5. The transponder of claim 1, wherein reference terminals of the rectified outputs of the bridges are isolated from each other or connected by a resistive element.

6. A method of supplying power to a transponder, comprising:

receiving a wireless signal at the transponder;

rectifying a received signal at a first rectifier to obtain a first rectified signal that is output to a regulator and receiving a modulated output signal from a modulator on an output terminal of the first rectifier;

rectifying the received signal to obtain a second rectified signal;

regulating the first rectified signal; and

demodulating the second rectified signal.

7. The method of claim 6, further comprising:

powering a processor with the regulated signal;

processing the demodulated signal with the processor; and

modulating the processed signal.

8. The method of claim 6, further comprising filtering the first rectified signal before the first rectified signal is regulated.

9. The method of claim 6, further comprising filtering the second rectified signal before the second rectified signal is demodulated.

10. A system for powering a transponder, comprising:

a means for receiving a wireless signal at the transponder;

a first means for rectifying the received signal as a first rectified signal that is input to at least a regulator and to receive a modulator output on an output of the first means for rectifying;

a second means for rectifying the received signal as a second rectified signal;

a means for demodulating the second rectified signal as a demodulated signal; and

a means for processing the demodulated signal.

11. The system of claim 10, wherein the first means for rectifying has a greater current capacity than the second means for rectifying.

12. The system of claim 10, wherein the first means for rectifying has a greater surface area than the second means for rectifying.

13. The system of claim 10, wherein the means for processing is arranged to provide a processed signal to a means for modulating the modulator.

14. The system of claim 10, further comprising a means for filtering the first rectified signal and a means for filtering the second rectified signal.

15. A system for wireless communication, comprising:

a terminal that includes an antenna to transmit a wireless signal; and

a transponder electro-magnetically coupled to the terminal, the transponder including;

a first rectifying bridge having at least one input terminal coupled to an oscillating circuit and having an output terminal coupled to a voltage regulator that is arranged to provide a supply voltage and further coupled to the output of a modulator; and

a second rectifying bridge having at least one input terminal coupled to the oscillating circuit and having an output terminal coupled to a demodulator.

16. The system of claim 15, wherein the transponder further comprises a filter coupled between the first rectifying bridge and the regulator.

17. The system of claim 16, wherein the transponder further comprises a filter coupled between the second rectifying bridge and the demodulator.

18. The system of claim 15, wherein the modulator is coupled to a processing unit.

19. The system of claim 18, wherein the processing unit is arranged to receive a demodulated signal from the demodulator and to output a signal to the modulator.

20. The system of claim 15, wherein the first rectifying bridge has a greater current capacity than the second rectifying bridge.

21. The system of claim 15, wherein the first rectifying bridge has a greater surface area than the second rectifying bridge.

22. A transponder apparatus, comprising:

an oscillating circuit that includes an antenna coupled to at least one input terminal of a first rectifying unit and at least one input terminal of a second rectifying unit that has a smaller current capacity than the first rectifying unit;

a first filter coupled to an output terminal of the first rectifying unit and a input terminal of a voltage regulator arranged to provide a supply voltage;

a second filter coupled to an output terminal of the second rectifying unit and coupled to an input terminal of a demodulator that has an output coupled to a processing unit;

and a modulator that has at least one input terminal coupled the processing unit and an output terminal coupled to an output terminal of the first rectifying unit.

23. The apparatus of claim 22, wherein the first rectifying unit has a greater surface area than the second rectifying unit.

24. The apparatus of claim 22, wherein the first rectifying unit comprises a bridge rectifier and the second rectifying unit comprises a bridge rectifier.