Semiconductor integrated circuit device and contactless IC card

• US 7,357,330 B2
• Filed: 05/12/2006
• Issued: 04/15/2008
• Est. Priority Date: 02/05/2004
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Nakadai, Yutaka, Watanabe, Kazuki, Ozawa, Shinichi
• Primary Examiner(s): Le; Thien Minh
• Application Number:
  US11/432,378
• Publication Number:
  US 20060202043A1
• Time in Patent Office: 704 Days
• Field of Search: 235/491, 235/493, 235/486, 235/487, 235/380, 235/383, 235/384, 235/381, 235/375, 235/449, 340/10.34, 340/10.52, 340/825.7, 340/572.7
• US Class Current: 235/492
• 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 semiconductor integrated circuit device (IC) and a contactless IC card including a receiver circuit that is able to stably demodulate information signals superimposed on AC signals from an interrogator. The receiver circuit included in the IC is equipped with antenna terminals, a power supply circuit, and a filter circuit. The information signal from which a high frequency component was eliminated through the filter circuit is input via a capacitor to an inverting input terminal of an operational amplifier and a reference voltage is input to a non-inverting input terminal thereof. After the information signal is fed back through a feedback path to the non-inverting input terminal of the operational amplifier, that signal is amplified and the amplified information signal is binarised by a binarising circuit, thereby data transmitted from the interrogator is demodulated. The contactless IC card comprises an antenna coil and the IC including this receiver circuit.

Claims

1. A dual-type IC card comprising:

terminals for input and output which are not present on a surface of the dual-type IC card;

a coil that forms an antenna; and

a semiconductor integrated circuit device including a receiver circuit that demodulates an information signal superimposed on an AC signal received through the antenna,

wherein said receiver circuit comprising;

antenna terminals which are connected to said antenna;

a rectifying circuit which rectifies and smoothes said AC signal fed from said antenna to said antenna terminals;

a filter circuit which eliminates a high frequency component from an output signal of said rectifying circuit;

a capacitor;

an operational amplifier with a non-inverting input to which a first reference voltage is input;

a feedback path; and

a binarizing circuit,

wherein an output signal of said filter circuit is input via said capacitor to an inverting input of said operational amplifier, and

wherein an output signal of said operational amplifier is fed back through said feedback path to the inverting input terminal of said operational amplifier and then input to said binarizing circuit.

2. The dual-type IC card according to claim 1, wherein said feedback path comprises a first diode and a second diode, both being connected in parallel and oriented in reverse directions.

3. The dual-type IC card according to claim 2, wherein said first and second diodes are Schottky barrier diodes.

4. The dual-type IC card according to claim 2, wherein said first diode and said second diode are constructed from drain-gate connected MOS transistors.

5. The dual-type IC card according to claim 1, wherein said binarizing circuit comprises a voltage comparator to which said first reference voltage and the output signal of said operational amplifier are input.

6. The dual-type IC card according to claim 1, wherein said binarizing circuit comprises a voltage comparator to which a second reference voltage and an output voltage of said operational amplifier are input.

7. The dual-type IC card according to claim 1, wherein said binarizing circuit comprises a first voltage comparator to which a third reference voltage and the output voltage of said operational amplifier are input, a second comparator to which a fourth reference voltage and the output voltage of said operational amplifier are input, and a flip-flop circuit which changes the level of its output terminal voltage depending on said first voltage comparator output signal and said second voltage comparator output signal.

8. The dual-type IC card according to claim 1, wherein said feedback path comprises first diodes connected in the same direction and second diodes connected in the same direction, and said first diodes and second diodes are connected in parallel and oriented in reverse directions.

9. A contactless IC card comprising:

a coil that forms an antenna; and

semiconductor integrated circuit device including a receiver circuit that demodulates an information signal superimposed on an AC signal received through the antenna,

wherein said receiver circuit includes;

antenna terminals which are connected to said antenna;

a rectifying circuit which rectifies and smoothes said AC signal fed from said antenna to said antenna terminals;

a filter circuit which eliminates a high and low frequency component from an output signal of said rectifying circuit;

a capacitor;

an operational amplifier with a non-inverting input to which a first reference voltage is input;

a feedback path; and

a binarizing circuit,

wherein an output signal of said filter circuit is input via said capacitor to an inverting input of said operational amplifier, and

wherein an output signal of said operational amplifier is fed back through said feedback path to the inverting input terminal of said operational amplifier and then input to said binarizing circuit.

10. The contactless IC card according to claim 9, wherein said feedback path comprises a first diode and a second diode, both being connected in parallel and oriented in reverse directions.

11. The contactless IC card according to claim 10, wherein said first and second diodes are Schottky baffler diodes.

12. The contactless IC card according to claim 10, wherein said first diode and said second diode are constructed from drain-gate connected MOS transistors.

13. The contactless IC card according to claim 9, wherein said binarizing circuit comprises a voltage comparator to which said first reference voltage and the output signal of said operational amplifier are input.

14. The contactless IC card according to claim 9, said binarizing circuit comprises a voltage comparator to which a second reference voltage and an output voltage of said operational amplifier are input.

15. The contactless IC card according to claim 9, said binarizing circuit comprises a first voltage comparator to which a third reference voltage and the output voltage of said operational amplifier are input, a second comparator to which a fourth reference voltage and the output voltage of said operational amplifier are input, and a flip-flop circuit which changes the level of its output terminal voltage depending on said first voltage comparator output signal and said second voltage comparator output signal.

16. The contactless IC card according to claim 9, wherein said feedback path comprises first diodes connected in the same direction and second diodes connected in the same direction, and said first diodes and second diodes are connected in parallel and oriented in reverse directions.