Near-field communication (NFC) reader optimized for high performance NFC and wireless power transfer with small antennas
First Claim
Patent Images
1. A device for near-field communication (NFC) and wireless power transfer, comprising:
- an antenna resonant circuit that includesan antenna for transmitting and receiving signals,a switch and a resistor connected in series, the serially-connected switch and resistor being connected in parallel to the antenna, andan antenna matching circuit, connected in parallel to the serially-connected switch and resistor, for adjusting impedance of the antenna,the switch being configured to turn on or off to cause the antenna resonant circuit to enter respectively a high-Q mode in which the Q-factor of the antenna resonant circuit is no lower than 50, and a low-Q mode in which the Q-factor of the antenna resonant circuit is no higher than 25, andan antenna driver for driving the antenna through the switch, the resistor and the antenna matching circuit; and
a microcontroller (MCU) configured toturn off or on the switch, so as to switch a mode of the antenna resonant circuit between the high-Q mode and the low-Q mode, and control the antenna resonant circuit to transmit, via the antenna,an unmodulated carrier signal when the antenna resonant circuit is in the high-Q mode, so as to transfer wireless power, anda modulated signal when the antenna resonant circuit is in the low-Q mode, so as to perform near-field communication, whereinthe antenna resonant circuit has a lower bandwidth in the high-Q mode than in the low-Q mode.
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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.
42 Citations
14 Claims
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1. A device for near-field communication (NFC) and wireless power transfer, comprising:
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an antenna resonant circuit that includes an antenna for transmitting and receiving signals, a switch and a resistor connected in series, the serially-connected switch and resistor being connected in parallel to the antenna, and an antenna matching circuit, connected in parallel to the serially-connected switch and resistor, for adjusting impedance of the antenna, the switch being configured to turn on or off to cause the antenna resonant circuit to enter respectively a high-Q mode in which the Q-factor of the antenna resonant circuit is no lower than 50, and a low-Q mode in which the Q-factor of the antenna resonant circuit is no higher than 25, and an antenna driver for driving the antenna through the switch, the resistor and the antenna matching circuit; and a microcontroller (MCU) configured to turn off or on the switch, so as to switch a mode of the antenna resonant circuit between the high-Q mode and the low-Q mode, and control the antenna resonant circuit to transmit, via the antenna, an unmodulated carrier signal when the antenna resonant circuit is in the high-Q mode, so as to transfer wireless power, and a modulated signal when the antenna resonant circuit is in the low-Q mode, so as to perform near-field communication, wherein the antenna resonant circuit has a lower bandwidth in the high-Q mode than in the low-Q mode.
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2. The device of claim 1, further comprising
a modulator connected to the antenna driver, for generating the modulated signal to be transmitted by the antenna; -
a demodulator connected to the antenna, 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.
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3. The device of claim 1, wherein the antenna driver has output impedance smaller than 5 ohm.
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4. 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.
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5. The device of claim 1, wherein the MCU controls to switch the antenna resonant circuit between the high-Q mode and the low-Q mode in real-time.
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6. The device of claim 1, wherein the antenna matching circuit is a PI matching circuit.
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7. A device for near-field communication (NFC) and wireless power transfer, comprising:
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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, the multi-Q antenna matching circuit including a Q-factor tuning switch configured to be turned on and off, and a Q-factor tuning resistor connected in series with the Q-factor tuning switch, the multi-Q antenna matching circuit being so configured that the turning-off and turning-on of the Q-factor tuning switch cause the antenna resonant circuit to enter respectively a high-Q mode in which the Q-factor of the antenna resonant circuit is no lower than 50, and a low-Q mode in which the Q-factor of the antenna resonant circuit is no higher than 25, and an antenna driver for driving the antenna through the multi-Q antenna matching circuit; and a microcontroller (MCU) configured to turn off or on the Q-factor tuning switch, so as to switch a mode of the antenna resonant circuit between the high-Q mode and the low-Q mode, and control the antenna resonant circuit to transmit, via the antenna, an unmodulated carrier signal when the antenna resonant circuit is in the high-Q mode, so as to transfer wireless power, and a modulated signal when the antenna resonant circuit is in the low-Q mode, so as to perform near-field communication, the antenna resonant circuit having a lower bandwidth in the high-Q mode than in the low-Q mode, wherein the antenna matching circuit has an insertion loss smaller than 1 db.
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8. The device of claim 7, further comprising
a modulator connected to the antenna driver, for generating the modulated 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.
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9. The device of claim 7, wherein the multi-Q antenna matching circuit further includes an antenna matching circuit, connected in parallel to the serially-connected Q-factor tuning switch and Q-factor tuning resistor, for adjusting impedance of the antenna.
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10. The device of claim 9, wherein the antenna matching circuit is a PI matching circuit.
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11. The device of claim 7, wherein the antenna driver has output impedance smaller than 5 ohm.
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12. The device of claim 7, 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.
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13. The device of claim 7, wherein the MCU controls to switch the antenna resonant circuit between the high-Q mode and the low-Q mode in real-time.
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14. The device of claim 7, wherein the serially-connected Q-factor tuning resistor and Q-factor tuning switch are connected to the antenna in parallel.
Specification