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Chip card with field strength detector having a switch and load to limit damping to the measurement cycle

  • US 5,418,358 A
  • Filed: 07/28/1993
  • Issued: 05/23/1995
  • Est. Priority Date: 08/20/1992
  • Status: Expired due to Fees
First Claim
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1. A contactless and batteryless chip card havingan antenna coil,a transmission and reception stage which via an electromagnetic alternating field generated by a write/read unit supplies the chip card with energy and ensures bidirectional data transmission to the write/read unit,a functional circuit part having a function which is dependent on an application of the chip card, anda detector for determining a field strength of said electromagnetic alternating field transmitting energy to said chip card, said detector having a switch and a load, said load being switched parallel to said coil by said switch for determining the field strength of the electromagnetic alternating field when a measurement cycle signal which is supplied to said switch is generated.

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