Analog interface for autonomous data exchange circuit

• US 6,792,288 B1
• Filed: 01/08/2001
• Issued: 09/14/2004
• Est. Priority Date: 07/08/1998
• Status: Expired due to Term

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Billiot, Gérard
• Primary Examiner(s): CRAVER, CHARLES R
• Application Number:
  US09/743,428
• Time in Patent Office: 1,345 Days
• Field of Search: 455/66.1, 455/558, 455/41-- 4, 455/78-83, 455/90.3, 455/127.1, 455/572
• US Class Current: 455/558
• 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

Analogue interface (24) for an, information exchange circuit by amplitude modulation of a carrier wave, comprising an interface input (102, 104) intended to be connected to the terminals of an antenna (22), a demodulator (150) one output of which is connected to a logical unit (26) in the information exchange circuit, and means (106) of supplying a power supply voltage to the information exchange circuit. According to the invention, the interface also comprises means of rectifying and filtering (116, 118) the carrier wave, connected to one input of the demodulator (150) and a device (120, 122, 132) for regulating the said power supply voltage.

Application in particular to the identification and sorting of objects or persons.

Claims

1. An analogue interface (24) for an information exchange circuit by amplitude modulation of a carrier wave comprising:

an interface input (102, 104) intended to be connected to the terminals of an antenna (22),

a first rectifier (106) supplying a power supply voltage to the information exchange circuit, said first rectifier coupled to said interface input;

a second rectifier (116) coupled to said first interface input;

a filter (118) coupled to an output of said second rectifier; and

a demodulator (150) one output of which is connected to a logical unit (26) in the information exchange circuit, said second rectifier and filter coupled to one input of the demodulator (150) and a device (120, 122, 132) for regulating said power supply voltage.

2. The interface according to claim 1, wherein said regulation device comprises means (132) for modifying the impedance of the antenna (22) as a function of a rectified voltage output by said second rectifier (116) and said filter (118).

3. The interface according to claim 2, wherein said means (132) for modifying the impedance of the antenna comprise a controllable load connected to the interface input (102, 104) in parallel to the terminals of the antenna (22).

4. The interface according to claim 3, wherein said controllable load comprises a field effect transistor (134) in which the channel terminals (source and drain) are respectively coupled to the antenna terminals through resistances (136, 138).

5. The interface according to claim 4, wherein the values of the resistances (136, 138) are approximately identical.

6. The interface according to claim 2, wherein said regulation device comprises:

a reference voltage source (120), and

means for comparing the rectified voltage output by said second rectifier (116) and said filter (118), with the reference voltage, said comparison means being connected to a control input (130) applied to means (132) for modifying the antenna impedance to control the impedance modification means as a function of a difference in voltage between the rectified voltage and the reference voltage.

7. The interface according to claim 6, wherein said comparison means comprise an amplifier (122) with a positive input (124) coupled to said second rectifier (116), a negative input (126) connected to the reference voltage (120) source and a control output (128) connected to the impedance modification means (132).

8. The interface according to claim 7, wherein said second rectifier (116) and said filter (118) coupled to the demodulator through said comparison means, the amplifier output (128) being connected to the demodulator input (150).

9. The interface according to claim 7, wherein said amplifier (122) is an operational amplifier in which the non-inverting and inverting inputs form the positive and negative inputs respectively.

10. The interface according to claim 6, wherein said comparison means comprise a field effect transistor (300) with a grid (302) forming the negative input, a first channel terminal (304) forming the positive input and a second channel terminal (308) forming the output.

11. The interface according to claim 1, wherein said demodulator has an input directly connected to said second rectifier and said filter.

12. The interface according to claim 1, further comprising a clock signal generator (400) with an input connected to one of the terminals (102) of the antenna (22) and one output connected to the logical unit (26).

13. The interface according to claim 1, further comprising a second modulator (500) with one input connected to the logical unit (26) and one output connected to one of the antenna terminals (104).

14. The interface according to claim 1, wherein the frequency of the carrier wave is greater than 10 Megahertz.

15. Information exchange circuit comprising an interface according to claim 1.

16. Information exchange circuit comprising an interface according to claim 14.