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Contactless IC card system

  • US 20040251981A1
  • Filed: 07/08/2004
  • Published: 12/16/2004
  • Est. Priority Date: 06/10/1998
  • Status: Active Grant
First Claim
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1. A modulating circuit comprising:

  • first signal output means for outputting a first output signal having a first predetermined phase with respect to that of an input signal;

    second signal output means for outputting a second output signal having a second predetermined phase with respect to that of said input signal;

    gate means for gating at least second output signal;

    calculation means for adding or subtracting said first output signal and said second output signal; and

    controls means for controlling the operation of said gate means in response to a logic level of input data, wherein said first signal output means outputs said first output signal from a first antenna;

    said second signal output means outputs said second output signal from a second antenna; and

    said calculation means is formed by way of an electromagnetic coupling between said first antenna and said second antenna.

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