Chassis NFC antenna booster

• US 9,729,210 B2
• Filed: 05/27/2015
• Issued: 08/08/2017
• Est. Priority Date: 04/27/2015
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Lee, Hyungpyo, Jensen, Henrik Tholstrup
• Primary Examiner(s): Nguyen, Tu X
• Application Number:
  US14/723,230
• Publication Number:
  US 20160315667A1
• Time in Patent Office: 804 Days
• Field of Search: 4555621, 455121, 455274
• CPC Class Codes: H04B 5/24 Inductive coupling
• CPC Class Codes: H04B 5/26 using coils
• CPC Class Codes: H04B 5/72 for local intradevice communication
• CPC Class Codes: H04W 4/80 Services using short range communication, e.g. near-field communication [NFC], radio-frequency identification [RFID] or low energy communication

Abstract

A communication device used for near filed communications (NFC). The device includes circuitry that generates a differential signal for communication with an analog front end of the device. The analog front end includes an impedance matching network and an antenna. The antenna is disposed at a predetermined distance away from the boundary of a battery compartment. The antenna forms a single loop around the battery compartment and is coupled to the matching network either in a differential manner or a single ended manner. The communication device includes a protective back casing that is either metallic or plastic in nature. With the single loop antenna configuration, both types of back covers enable efficient NFC.

Claims

1. A communication device, comprising:

circuitry configured to generate a differential signal for communication with an analog front end, wherein the analog front end includes a matching network and an antenna, the antenna being disposed around a boundary of a battery compartment of the communication device, and the matching network comprising

a first capacitor having a first end directly connected to a first end of the antenna, and a second end directly connected to a second end of the antenna,

a second capacitor having a first end connected to a ground terminal, and a second end directly connected to a first transmit port of circuitry, and

a third capacitor having a first end connected to the ground terminal, and a second end directly connected to a second transmit port of the circuitry.

2. The communication device of claim 1, wherein the antenna is a wire that forms a single loop around the battery compartment.

3. The communication device of claim 2, wherein the wire is disposed at a distance of one millimeter away from the boundary of the battery compartment.

4. The communication device of claim 1, wherein the antenna is a trace that is embedded on a printed circuit board of the communication device.

5. The communication device of claim 1, wherein the antenna couples to the matching network in one of a differential fashion and a single ended fashion, and the matching network couples to the circuitry in a differential fashion.

6. The communication device of claim 5, wherein when the antenna couples to the matching network in the differential fashion, both ends of the antenna are symmetrically connected to two ends of the matching network, and when the antenna couples to the matching network in the single ended fashion, one end of the antenna is connected to the matching network and the other end is connected to a ground terminal.

7. The communication device of claim 1, wherein the battery compartment houses a battery of the communication device and, wherein the battery of the communication device does not include an antenna that is disposed on the surface of the battery or is embedded within the battery.

8. The communication device of claim 1, wherein the antenna has an impedance of 50 ohms at a resonance frequency of 13.56 MHz.

9. The communication device of claim 1, wherein the antenna has a quality factor of 30.

10. A communication device comprising:

a protective back casing;

an antenna disposed around a boundary of a battery compartment of the communication device; and

a matching network comprising

a first capacitor having a first end directly connected to a first end of the antenna, and a second end directly connected to a second end of the antenna,

a second capacitor having a first end connected to a ground terminal, and a second end directly connected to a first transmit port of circuitry configured to generate a differential signal for communication with the matching network, and

a third capacitor having a first end connected to the ground terminal, and a second end directly connected to a second transmit port of the circuitry.

11. The communication device of claim 10, wherein the antenna is a wire that forms a single loop around the battery compartment and is disposed at a distance of one millimeter away from the boundary of the battery compartment.

12. The communication device of claim 10, wherein the antenna is a trace that is embedded on a printed circuit board of the communication device.

13. The communication device of claim 10, wherein the matching network couples to the circuitry in a differential fashion and couples to the antenna in one of a differential fashion and a single ended fashion.

14. The communication device of claim 10, wherein the protective back casing is one of a plastic back casing and a metallic back casing.

15. The communication device of claim 10, wherein the antenna has an impedance of 50 ohms at a resonance frequency of 13.56 MHz.

16. The communication device of claim 10, wherein the antenna has a quality factor of 30.