NEAR-FIELD COMMUNICATION (NFC) READER OPTIMIZED FOR HIGH PERFORMANCE NFC AND WIRELESS POWER TRANSFER WITH SMALL ANTENNAS

• US 20170288734A1
• Filed: 03/17/2017
• Published: 10/05/2017
• Est. Priority Date: 04/01/2016
• Status: Active Grant

• Current Assignee: Hangzhou Chivotech Limited
• Original Assignee: Fusens Technology Limited
• Inventors: ZHOU, Ruogu, WANG, Qingbin
• Granted Patent: US 10,153,809 B2
• Time in Patent Office: Days
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H04B 5/24 Inductive coupling
• 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

A device for near-field communication (NFC) and wireless power transfer. The device has an antenna resonant circuit that includes an antenna for transmitting and receiving signals, a multi-Q antenna matching circuit for adjusting a Q-factor of the antenna resonant circuit, and an antenna driver for driving the antenna through the multi-Q antenna matching circuit. The device also includes a microcontroller (MCU) configured to control the multi-Q antenna matching circuit to switch between a high-Q mode for wireless power transfer and a low-Q mode for NFC.

Claims

1. A device for near-field communication (NFC) and wireless power transfer, comprising:

an antenna resonant circuit that includes

an antenna for transmitting and receiving signals,

a multi-Q antenna matching circuit for adjusting a quality factor (Q-factor) of the antenna resonant circuit, and

an antenna driver for driving the antenna through the multi-Q antenna matching circuit; and

a microcontroller (MCU) for controlling the multi-Q antenna matching circuit, the MCU being configured to control the multi-Q antenna matching circuit to switch between a high-Q mode for the wireless power transfer and a low-Q mode for the NFC.

2. The device of claim 1, further comprising

a modulator connected to the antenna driver, for modulating a signal to be transmitted by the antenna;

a demodulator connected to the antenna via the multi-Q antenna matching circuit, for demodulating a signal received by the antenna, the demodulator and modulator being connected to the MCU;

a data interface connected to the MCU via a FIFO (first in first out buffer) for data exchange with another device;

a power supply for providing power to the device; and

a clock system for providing clock signals to the device.

3. The device of claim 1, wherein the multi-Q antenna matching circuit includes

an antenna matching circuit for adjusting impedance of the antenna, and

a Q-factor tuning circuit for adjusting the Q-factor of the antenna resonant circuit.

4. The device of claim 1, wherein the Q-factor tuning circuit is connected in parallel to the antenna, and includes

a Q-factor tuning switch that is controllable by the MCU, and

a Q-factor tuning resistor connected in series with the Q-factor tuning switch.

5. The device of claim 4, wherein the antenna matching circuit has an insertion loss smaller than 1 db.

6. The device of claim 1, wherein the antenna driver has output impedance smaller than 5 ohm.

7. The device of claim 1, wherein the antenna has

an inductance in a range of 1 uH to 10 uH,

an area in a range of 100 mm² to 5000 mm², and

a Q value higher than 100.

8. The device of claim 1, wherein

the high-Q mode is a mode in which the Q-factor of the antenna resonant circuit is no lower than 50, and

the low-Q mode is a mode in which the Q-factor of the antenna resonant circuit is no higher than 25.

9. The device of claim 1, wherein the MCU controls to switch the multi-Q antenna matching circuit between the high-Q mode and the low-Q mode in real-time.