MULTICHANNEL TRANSPONDER AND A METHOD OF DETERMINING A MOST STRONGLY COUPLED CHANNEL OR MORE STRONGLY COUPLED CHANNELS

• US 20150031311A1
• Filed: 07/01/2014
• Published: 01/29/2015
• Est. Priority Date: 07/25/2013
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Simons, Sven
• Granted Patent: US 9,543,989 B2
• Time in Patent Office: Days
• US Class Current: 455/73
• CPC Class Codes: G06K 19/0726 the arrangement including a circuit for tuning the resonance frequency of an antenna on the record carrier
• CPC Class Codes: H04B 1/0064 with separate antennas for the more than one band H04B1/0053 takes precedence
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/45 Transponders

Abstract

A transponder is disclosed comprising a multichannel front-end circuit; each channel of the multichannel front-end circuit a resonant circuit associated with a respective antenna and producing, in use, an input voltage; a conditioning circuit configured to provide a conditioned input voltage from the input voltage, and a comparator configured to compare the conditioned input voltage with a reference voltage; wherein the front-end circuit further comprises: a variable load connectable across each of the resonant circuits, and a controller configured to, in use, vary the variable load and detect an output from each of the comparators.

A method of operating such a transponder to determine a most strongly coupled channel, or more strongly coupled channels, is also disclosed.

Claims

1. A transponder comprising a multichannel front-end circuit;

each channel of the multichannel front-end circuit comprising;

a resonant circuit associated with a respective antenna and producing, in use, an input voltage;

a conditioning circuit configured to provide a conditioned input voltage from the input voltage, and

a comparator configured to compare the conditioned input voltage with a reference voltage;

wherein the front-end circuit further comprises;

a variable load connectable across each of the resonant circuits, and a controller configured to, in use, vary the variable load and detect an output from each of the comparators.

2. A transponder according to claim 1, in which the conditioning circuit comprises a rectifier for rectifying the input voltage.

3. A transponder according to claim 2, wherein the conditioning circuit further comprises a parallel arrangement of a capacitor and a resistor, for producing a voltage envelope.

4. A transponder according to claim 1, in which the variable load is stepwise variable.

5. A transponder according to claim 1, in which a separate respective variable load is connectable across each of the resonant circuits.

6. A transponder according to claim 1, wherein the antennae are configured to be coupled, in use, to the near field of the electromagnetic field.

7. A transponder according to claim 1, wherein the antennae are configured to be coupled, in use, to the far field of the electromagnetic field.

8. A method of operating a transponder having a multichannel front-end circuit, and being in an electromagnetic field, wherein each channel comprises a resonant circuit associated with a respective antenna, the method comprising:

varying a load across each of the resonant circuits;

comparing a respective conditioned input voltage derived from a respective voltage across each of the resonant circuits with a predetermined reference voltage; and

determining at least one of which channel is most strongly coupled to the field and which channels are more strongly coupled to the field, in response to the comparisons.

9. The method of claim 8, wherein the voltage across each resonant circuit is rectified, and then connected to a ground by a parallel arrangement of a capacitor and a resistor, to derive the respective conditioned input voltage.

10. The method of claim 8, in which a separate respective variable load is connectable across each of the resonant circuits.

11. The method of claim 8, wherein the varying a load across each of the resonant circuits comprises a stepwise variation of the load.

12. The method of claim 8, wherein the antennae are configured to be coupled, in use, to the near field of the electromagnetic field.