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METHOD FOR A BATTERY AND PASSIVE POWER SUPPLY TO AN RFID TAG AND A SWITCHING CIRCUIT FOR CARRYING OUT SAID METHOD

  • US 20110241842A1
  • Filed: 12/16/2009
  • Published: 10/06/2011
  • Est. Priority Date: 12/16/2008
  • Status: Active Grant
First Claim
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1. A method for battery power supply and passive power supply to an RFID tag, which is provided with a battery (b) and situated in a radio-frequency radiation field, characterized inthat a value of a battery voltage (Vbat) is checked whenever the battery (b) is connected orwhenever a rectified voltage (Vrect) obtained by rectifying a voltage induced in an antenna (a) due to the radio-frequency radiation field reaches a preset value,that, in case of an acceptable value of the battery voltage (Vbat),circuits of the RFID tag are energized by the battery (b) through a controlled switching circuit (csc),across which the battery voltage (Vbat) drops by a voltage drop across an open PMOS transistor,and that, in case of an unacceptable value of the battery voltage (Vbat) andafter a termination of a time delay after the rectified voltage (Vrect)obtained by rectifying the voltage induced in the antenna (a) due to the radio-frequency radiation field exceeded the preset value,circuits of the RFID tag are energized by a rectifier rectifying said induced voltage through the controlled switching circuit (csc),across which the output voltage (Vrect) of said rectifier drops by the voltage drop across the open PMOS transistor.

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