Circuit arrangement for wirelessly exchanging data and RFID chip card device

• US 7,912,430 B2
• Filed: 02/02/2007
• Issued: 03/22/2011
• Est. Priority Date: 10/13/2006
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Sbuell, Richard, Kargl, Walter
• Primary Examiner(s): Anderson; Matthew D
• Assistant Examiner(s): GONZALES, APRIL GUZMAN
• Application Number:
  US11/670,855
• Publication Number:
  US 20080087723A1
• Time in Patent Office: 1,509 Days
• Field of Search: 455/41.2, 455/41.1, 455/126, 235/435, 363/16, 363/89, 363/70, 363/81, 363/125, 363/84, 340/10.34, 323/234, 330/85, 330/2, 330/140, 330/129, 330/141, 330/51
• US Class Current: 455/126
• 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: H04B 5/00 Near-field transmission systems, e.g. inductive or capacitive transmission systems

Abstract

A circuit arrangement for wirelessly exchanging data with a reader device, including an antenna for converting electromagnetic radiation into an antenna voltage, an analogue circuit for demodulating an information signal based on the antenna voltage, and a digital circuit for processing of the information signal and for receiving power from the analogue circuit. The circuit arrangement also includes a decoupling circuit, which is interconnected between the analogue circuit and the digital circuit and provides a decoupling of both circuits.

Claims

1. A circuit arrangement for wirelessly exchanging data with a reader device, comprising:

an antenna configured to convert electromagnetic radiation into an antenna voltage;

an analogue circuit configured to demodulate an information signal based on the antenna voltage, the analogue circuit comprising an adjustable shunt;

a digital circuit configured to process the information signal and receive power from the analogue circuit;

a decoupling circuit interconnected between the analogue circuit and the digital circuit; and

a feedback circuit, which is connected to the decoupling circuit and the adjustable shunt, configured to detect an amplitude modulation of the antenna voltage, wherein the feedback circuit controls the adjustable shunt in response to a detected modulation of the antenna voltage.

2. The circuit arrangement according to claim 1, wherein, in a predefined voltage range, the decoupling circuit draws a constant current from the analogue circuit independent from the power supplied to the digital circuit.

3. The circuit arrangement according to claim 2, wherein the decoupling circuit comprises a first control input for receiving a first control signal for controlling the constant current drawn from the analogue circuit by the decoupling circuit.

4. The circuit arrangement according to claim 3, wherein the decoupling circuit comprises an adjustable current source that is adjusted using the first control signal.

5. The circuit arrangement according to claim 2, wherein the analogue circuit is configured to perform a load modulation, and wherein an impedance of the analogue circuit is controllable by a load modulator independently from the power supplied to the digital circuit.

6. The circuit arrangement according to claim 1, wherein the decoupling circuit comprises a voltage output for providing a supply voltage to the digital circuit and a second control input for receiving a second control signal for controlling the supply voltage provided at the voltage output.

7. The circuit arrangement according to claim 6, wherein the decoupling circuit comprises an adjustable Zener-diode or a self-regulating transistor configured to control the supply voltage based on the second control signal.

8. The circuit arrangement according to claim 1, wherein the feedback circuit is configured to keep constant or decreasing decrease the impedance of the adjustable shunt when a gap is detected in the modulated antenna voltage.

9. A circuit arrangement for wirelessly exchanging data with a reader device, comprising:

an antenna configured to convert electromagnetic radiation into an antenna voltage;

an analogue circuit configured to demodulate an information signal based on the antenna voltage;

a digital circuit configured to process the information signal and receive power from the analogue circuit;

a decoupling circuit interconnected between the analogue circuit and the digital circuit; and

a control circuit configured to monitor a parameter characterizing the field strength of an electromagnetic field surrounding the antenna and adjust an input current of the decoupling circuit based on the monitored parameter.

10. The circuit arrangement according to claim 9, wherein in a predefined voltage range, the decoupling circuit is configured to draw a constant current from the analogue circuit independent from the power supplied to the digital circuit.

11. The circuit arrangement according to claim 10, wherein the decoupling circuit comprises a first control input for receiving a first control signal for controlling the constant current drawn from the analogue circuit by the decoupling circuit.

12. The circuit arrangement according to claim 11, wherein the decoupling circuit comprises an adjustable current source that is adjusted using the first control signal.

13. The circuit arrangement according to claim 10, wherein the analogue circuit is configured to perform a load modulation, and wherein an impedance of the analogue circuit is controllable by a load modulator independently from the power supplied to the digital circuit.

14. The circuit arrangement according to claim 9, wherein the decoupling circuit comprises a voltage output for providing a supply voltage to the digital circuit and a second control input for receiving a second control signal for controlling the supply voltage provided at the voltage output.

15. The circuit arrangement according to claim 14, wherein the decoupling circuit comprises an adjustable Zener-diode or a self-regulating transistor configured to control the supply voltage based on the second control signal.

16. The circuit arrangement according to claim 9, wherein the control circuit comprises a control output for outputting a control signal for activating an energy saving state of the digital circuit.

17. The circuit arrangement according to claim 16, wherein the control output is connected to a clock generator configured to provide a clock signal to the digital circuit, and wherein the control signal is for reducing the clock rate of a clock signal supplied by the clock generator.

18. A circuit arrangement for wirelessly exchanging data with a reading means, comprising:

a conversion means for converting electromagnetic radiation into an antenna voltage;

a demodulation means for demodulating an information signal based on the antenna voltage;

an adjustable shunting means for shunting a current caused by the antenna voltage;

a processing means for processing of the information signal;

an interconnection means for supplying power from the conversion means to the processing means and for decoupling the conversion means from the processing means; and

a feedback means for detecting an amplitude modulation of the antenna voltage and for controlling the adjustable shunting means in response to a detected modulation of the antenna voltage.

19. A circuit arrangement for wirelessly exchanging data with a reading means, comprising:

an conversion means for converting electromagnetic radiation into an antenna voltage;

a demodulation means for demodulating an information signal based on the antenna voltage;

a processing means for processing the information signal;

an interconnection means for supplying power from the conversion means to the processing means and for decoupling the conversion means from the processing means; and

a control means for monitoring a parameter characterizing the field strength of an electromagnetic field surrounding the conversion means and for adjusting an input current of the interconnection means based on the monitored parameter.

20. The circuit arrangement according to claim 19, further comprising a clock generation means for providing a clock signal to the processing means, wherein the control means controls a reduction of the clock rate of the clock signal supplied by the clock generation means.

21. An RFID chip card device for wirelessly exchanging data with a RFID reader device, comprising:

an antenna configured to convert electromagnetic radiation into an antenna voltage;

an analogue circuit configured to demodulate an information signal based on the antenna voltage, the analogue circuit comprising an adjustable shunt;

a digital circuit configured to process the information signal and receive power from the analogue circuit;

a decoupling circuit interconnected between the analogue circuit and the digital circuit; and

a feedback circuit, which is connected to the decoupling circuit and the adjustable shunt, is configured to detect an amplitude modulation of the antenna voltage, wherein the feedback circuit is configured to control the adjustable shunt in response to a detected modulation of the antenna voltage.

22. The RFID chip card device according to claim 21, further comprising an adjustable current source that is adjustable using a first control signal controlling the constant current drawn from the analogue circuit by the decoupling circuit.

23. The RFID chip card device according to claim 21, wherein the feedback circuit is configured to keep constant or decrease the impedance of the adjustable shunt when a gap is detected in the modulated antenna voltage.

24. An RFID chip card device for wirelessly exchanging data with an RFID reader device, comprising:

an antenna configured to convert electromagnetic radiation into an antenna voltage;

an analogue circuit configured to demodulate an information signal based on the antenna voltage;

a digital circuit configured to process the information signal and receive power from the analogue circuit;

a decoupling circuit interconnected between the analogue circuit and the digital circuit; and

a control circuit configured to monitor a parameter characterizing the field strength of an electromagnetic field surrounding the antenna and adjust an input current of the decoupling circuit based on the monitored parameter.

25. The RFID chip card device according to claim 24, further comprising a clock generator configured to provide a clock signal to the digital circuit, wherein the control circuit is configured to provide a control signal for reducing the clock rate of the provided clock signal to the clock generator.