Transponder and method for operating a transponder

A method for operating an RFID transponder, comprising:

• determining a quantity which is derivable from a field strength of an electromagnetic field that is prevailing at the location of the RFID transponder;
• comparing the determined quantity derived with a threshold value;
• and
• deactivating a functionality of the RFID transponder if the quantity derived falls below the threshold value, wherein the threshold value is based on the adjustable response field strength, which is higher than the minimum field strength required for the operation of the RFID transponder.

A computer program for performing a method for operating an RFID transponder, the method comprising:

• determining a quantity which is derivable from a field strength of an electromagnetic field that is prevailing at the location of the RFID transponder;
• comparing the determined quantity derived with a threshold value;
• and
• deactivating a functionality of the RFID transponder if the quantity derived falls below the threshold value, wherein the threshold value is based on the adjustable response field strength, which is higher than the minimum field strength required for the operation of the RFID transponder,
• when the computer program runs on a computer and/or a microcontroller.

A transponder comprising:

• a determination circuit formed to determine a quantity which is derivable from a field strength of an electromagnetic field prevailing at the location of the transponder;
• a comparator formed to compare the determined quantity derived from the field strength with a threshold value;
• a deactivator formed to deactivate a functionality of the transponder if the derived quantity falls below the threshold value;
• and
• a load circuit, and in which the determination circuit includes a measurement circuit to detect a residual power signal depending upon part of the energy provided by the electromagnetic field that is not needed by the load circuit,
• wherein the load circuit is a clocked load circuit, and wherein the determination circuit is formed to determine, for the load circuit, a clock frequency of a clock signal that depends upon the prevailing field strength by means of the residual power signal, and
• wherein the determination circuit includes a comparator assembly to compare a target value with the determined residual power signal and to increase the clock frequency if the detected residual power signal is greater than the target value, and to decrease the clock frequency if the detected residual power signal is smaller than the target value, based on the comparison.

A transponder comprising:

• a determination circuit formed to determine a quantity which is derivable from a field strength of an electromagnetic field prevailing at the location of the transponder;
• a comparator formed to compare the determined quantity derived from the field strength with a threshold value;
• a deactivator formed to deactivate a functionality of the RFID transponder if the derived quantity falls below the threshold value;
• and
• a load circuit, and in which the determination circuit includes a measurement circuit to detect a residual power signal depending upon part of the energy provided by the electromagnetic field that is not needed by the load circuit,
• wherein the determination means is formed to determine, by means of the residual power signal, an electrical conductance of the load circuit with which an electrical power consumption of the load circuit may be adapted to the part of the energy provided by the electromagnetic field that is not needed, and
• wherein the determination circuit includes a comparison assembly to compare a target value with the detected residual power signal to increase the electrical conductance of the load circuit if the detected residual power signal is greater than the target value, and to decrease the electrical conductance of the load circuit if the detected residual power signal is smaller than the target value, based on the comparison.