NFC SYSTEM WAKEUP WITH ENERGY HARVESTING

• US 20180034507A1
• Filed: 08/01/2016
• Published: 02/01/2018
• Est. Priority Date: 08/01/2016
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Wobak, Markus, Kormann, Leonhard, Schroeder, Juergen
• Granted Patent: US 10,680,677 B2
• Time in Patent Office: Days
• CPC Class Codes: H04B 5/45 Transponders
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04B 5/77 for interrogation
• CPC Class Codes: H04B 5/79 for data transfer in combination with power transfer

Abstract

The present invention provides for a system that makes use of a system power supply enable switch controlled by a near field communications (NFC) frontend with energy harvesting. In one embodiment, RF power in the 13.56 MHz band generated by a NFC counterpart (such as a mobile phone) is detected by the energy harvesting unit being part of the battery-unpowered NFC communication device. After activation, the system can perform actions required to communicate to the presented device (i.e., the NFC counterpart). Later, the system can switch itself into the unpowered state again. In another embodiment, this feature can also be used to control an NFC protection circuitry very quickly after the NFC device is exposed to an external HF (high frequency) field.

Claims

1. A method comprising:

detecting, by an energy harvesting unit associated with a near field communication (NFC) system, an active external radio frequency (RF) field;

generating, by the energy harvesting unit associated with the NFC system in response to the detecting, an output signal; and

using the output signal to enable a switch to a power supply or an NFC protection circuit,

wherein the switch allows for the power supply to provide power to the NFC system, or the switch allows for the NFC protection circuit to protect the NFC system.

2. The method of claim 1, wherein the energy harvesting unit is capable of supplying power to the NFC system without using power from a battery.

3. The method of claim 1, wherein the energy harvesting unit is a part of an NFC communication device that is not powered by a battery.

4. The method of claim 1, wherein the energy harvesting unit comprises:

a bridge rectifier circuit, and

a blocking capacitor.

5. The method of claim 1, wherein the energy harvesting unit derives a direct current (DC) voltage out of an alternating current (AC) high frequency (HF) field.

6. The method of claim 1, wherein the power supply is a system power supply.

7. The method of claim 1, wherein the active external radio frequency (RF) field is generated by an NFC counterpart device.

8. The method of claim 7, wherein the NFC counterpart device is a mobile phone.

9. The method of claim 1, wherein the switch to the power supply or the NFC protection circuit remains enabled even when the energy harvesting unit no longer detects the active external radio frequency (RF) field.

10. The method of claim 9, further comprising:

disabling, by the NFC system, the switch to the power supply or the NFC protection circuit,

wherein the NFC system comprises a NFC frontend and other parts.

11. The method of claim 9, further comprising:

disabling, by a second system, the switch to the power supply or the NFC protection circuit,

wherein the NFC system comprises a NFC frontend and other parts,

wherein the second system is different from the NFC system.

12. A device comprising:

an energy harvesting unit associated with a near field communication (NFC) system, the energy harvesting unit configured to detect an active external radio frequency (RF) field, the energy harvesting unit configured to generate an output signal in response to detecting the active external radio frequency (RF) field; and

a switch to enable or disable a power supply, the switch configured to enable the power supply in response to receiving the output signal,

wherein the switch allows for the power supply to provide power to the device.

13. The device of claim 12, wherein the energy harvesting unit is capable of supplying power to the NFC system without using power from a battery.

14. The device of claim 12, wherein the energy harvesting unit comprises:

a bridge rectifier circuit, and

a blocking capacitor.

15. The device of claim 12, wherein the energy harvesting unit derives a direct current (DC) voltage out of an alternating current (AC) high frequency (HF) field.

16. The device of claim 12, wherein the active external radio frequency (RF) field is generated by an NFC counterpart device.

17. The device of claim 12, wherein the switch is further configured to remain enabled even when the energy harvesting unit no longer detects the active external radio frequency (RF) field.

18. The device of claim 17,

wherein the device is further comprising of other parts,

wherein the device is configured to use the switch to disable the power supply.

19. A device comprising:

an energy harvesting unit associated with a near field communication (NFC) system, the energy harvesting unit configured to detect an active external radio frequency (RF) field, the energy harvesting unit configured to generate an output signal in response to detecting the active external radio frequency (RF) field; and

a switch to enable or disable an NFC protection circuit, the switch configured to enable the NFC protection circuit in response to receiving the output signal,

wherein the switch allows for the NFC protection circuit to protect the device.

20. The device of claim 19, wherein the switch is further configured to remain enabled even when the energy harvesting unit no longer detects the active external radio frequency (RF) field.