Evaluation of the coupling factor of an electromagnetic transponder by capacitive detuning
AssigneeSTMicroelectronics (Rousset) SAS
InventorLuc Wuidart
Life of this patent
Estimating the term…
Abstract
A method for evaluating the current coupling factor between an electromagnetic transponder and a terminal, and a transponder implementing this method, wherein a ratio between data representative of a voltage across an oscillating circuit of the transponder and obtained for two capacitance values of the oscillating circuit is compared with one or several thresholds.
Claims37
A method for evaluating a current coupling factor between an electromagnetic transponder and a terminal, comprising acts of:
- obtaining, by the electromagnetic transponder, a ratio between data representative of a voltage across an oscillating circuit of the transponder for two capacitance values of the oscillating circuit;
- and
- comparing, by the electromagnetic transponder, the ratio with at least one threshold to provide a result indicative of the current coupling factor, wherein the at least one threshold is selected based on one or both of the two capacitance values.
A method for evaluating a current coupling factor between a terminal and an electromagnetic transponder having an oscillating circuit, comprising acts of:
- measuring, by the transponder, a first value representative of a voltage across the oscillating circuit with a first capacitance value associated with the oscillating circuit;
- measuring, by the transponder, a second value representative of the voltage across the oscillating circuit with a second capacitance value associated with the oscillating circuit;
- determining, by the transponder, a ratio of the first value to the second value;
- and
- comparing, by the transponder, the ratio to at least one threshold, wherein a result of the comparing is indicative of the current coupling factor, and wherein the at least one threshold is selected based on one or both of the two capacitance values.
An electromagnetic transponder comprising:
- an oscillating circuit;
- and
- a processing circuit configured to evaluate a current coupling factor between a terminal and the electromagnetic transponder, wherein the processing circuit is configured to:
- measure a first value representative of a voltage across the oscillating circuit with a first capacitance value associated with the oscillating circuit;
- measure a second value representative of the voltage across the oscillating circuit with a second capacitance value associated with the oscillating circuit;
- determine a ratio of the first value to the second value;
- and
- compare the ratio to at least one threshold, wherein a result of the comparison is indicative of the current coupling factor, and wherein the at least one threshold is selected based on one or both of the two capacitance values.
Dependencies are inferred from the claim text.