Metal oxide semiconductor device for use in UHF electronic article surveillance systems
An Electronic Article Surveillance (“EAS”) tag and method and system for deactivating EAS tags without the need to physically contact the tag with a deactivation device. The EAS tag replaces the conventional diode with a non-linear device such as a metal-oxide-semiconductor (“MOS”) capacitor with a given breakdown voltage threshold. Inducing a predetermined voltage across the MOS capacitor results in destruction of the MOS capacitor rendering the EAS tag undetectable in the EAS interrogation system.
1. An electronic article surveillance (“EAS”) tag comprising:
an antenna circuit; and
a non-linear component electrically coupled to the antenna circuit, the non-linear component exhibiting a non-linear capacitance with respect to voltage below a breakdown voltage threshold and exhibiting irreversible linear capacitance with respect to voltage above the breakdown voltage threshold.
2. The electronic article surveillance (“EAS”) tag of claim 1 , wherein the non-linear component is a metal-oxide-semiconductor (“MOS”) device.
3. The electronic article surveillance (“EAS”) tag of claim 2 , wherein application of a predetermined voltage to the MOS device results in destruction of the MOS device, thereby rendering the EAS tag undetectable by an EAS interrogation system.
4. The electronic article surveillance (“EAS”) tag of claim 3 , wherein the MOS device includes an insulator layer, wherein application of the predetermined voltage to the MOS device results in electrical breakdown of the insulation layer.
5. The electronic article surveillance (“EAS”) tag of claim 3 , further comprising a step-up circuit electrically coupled to the MOS device, the step-up circuit increasing the voltage applied to the MOS device.
6. The electronic article surveillance (“EAS”) tag of claim 5 , wherein the step-up circuit includes a switch that is activated at a predetermined voltage, making the increased voltage available to the MOS device.
7. The electronic article surveillance (“EAS”) tag of claim 1 , wherein the antenna circuit includes a dipole antenna.
8. The electronic article surveillance (“EAS”) tag of claim 1 , wherein the antenna circuit includes a first portion and a second portion, and the non-linear component being located between the first portion of the antenna circuit and the second portion of the antenna circuit.
9. The electronic article surveillance (“EAS”) tag of claim 1 , wherein the EAS tag is a mixing tag modulated by a combination of high frequency and low frequency signals.
10. An electronic article surveillance (“EAS”) tag deactivation system comprising:
an EAS tag, the tag comprising:
an antenna circuit; and
a non-linear component electrically coupled to the antenna circuit, the non-linear component exhibiting a non-linear capacitance with respect to voltage below a breakdown voltage threshold and exhibiting irreversible linear capacitance with respect to voltage above the breakdown voltage threshold; and
a deactivation device adapted to deactivate the EAS tag without making contact with it.
11. The system of claim 10 , wherein the non-linear component is a metal-oxide-semiconductor (“MOS”) device.
12. The system of claim 11 , wherein the deactivation device applies a predetermined voltage across the MOS resulting in destruction of the MOS device, thereby rendering the EAS tag undetectable by an EAS interrogation system.
13. The system of claim 12 , wherein the MOS device includes an insulator layer, wherein application of the predetermined voltage to the MOS device results in breakdown of the insulation layer.
14. The system of claim 12 , further comprising a step-up circuit electrically coupled to the MOS device, the step-up circuit increasing the voltage applied the MOS device.
15. The system of claim 14 , wherein the step-up circuit includes a switch that is activated at a predetermined voltage, making the increased voltage available to the MOS device.
16. The system of claim 10 , wherein the antenna circuit includes a dipole antenna.
17. The system of claim 10 , wherein the antenna circuit includes a first portion and a second portion, and the non-linear component being located between the first portion of the antenna circuit and the second portion of the antenna circuit.
18. The system of claim 10 , wherein the EAS tag is a mixing tag modulated by a combination of high frequency and low frequency signals.
19. A method of deactivating an electronic article surveillance (“EAS”) tag, the method comprising:
providing an EAS tag having an antenna circuit and a non-linear component electrically coupled to the antenna circuit, the non-linear component exhibiting a non-linear capacitance with respect to voltage below a breakdown voltage threshold and exhibiting irreversible linear capacitance with respect to voltage above the breakdown voltage threshold; and
inducing a voltage across the non-linear component, the induced voltage being greater than the breakdown threshold in order to breakdown the non-linear component.
20. The method of claim 19 , wherein the non-linear component is a metal-oxide-semiconductor (“MOS”) device.