Near field communications reader
First Claim
Patent Images
1. A near field communications (NFC) reader, comprising:
- an amplifier configured to drive an antenna of the NFC reader;
a first antenna filter comprising a first variable resistance and a first capacitor connected in series with the antenna;
a first switch connected in parallel with the first capacitor;
a controller configured to;
adjust a quality factor of the antenna by adjusting the first variable resistance; and
control an operation of the first switch based on a data rate of data to be transmitted by the NFC reader;
a second antenna filter comprising a second variable resistance and a second capacitor connected in series with the antenna; and
a second switch connected in parallel with the second capacitor and configured to increase the bandwidth available for data transmission by the NFC reader by short-circuiting the second capacitor.
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Abstract
The present application relates to a near field communications (NFC) reader having a power amplifier which has an output that connects to an input terminal of an antenna by means of an antenna filter made up of one or more series resistors and one or more series capacitors. The NFC reader includes means for adjusting the Q factor of the antenna so as to increase the available transmit bandwidth and/or improve the efficiency of the reader. The means for adjusting the Q factor of the antenna may be, for example, a variable resistive component or one or more switches.
29 Citations
20 Claims
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1. A near field communications (NFC) reader, comprising:
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an amplifier configured to drive an antenna of the NFC reader; a first antenna filter comprising a first variable resistance and a first capacitor connected in series with the antenna; a first switch connected in parallel with the first capacitor; a controller configured to; adjust a quality factor of the antenna by adjusting the first variable resistance; and control an operation of the first switch based on a data rate of data to be transmitted by the NFC reader; a second antenna filter comprising a second variable resistance and a second capacitor connected in series with the antenna; and a second switch connected in parallel with the second capacitor and configured to increase the bandwidth available for data transmission by the NFC reader by short-circuiting the second capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A near field communications (NFC) reader, comprising:
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an antenna including a first terminal and a second terminal; a differential amplifier including a first terminal and a second terminal; a single first variable resistor and a single first capacitor connected in series between the first terminal of the differential amplifier and the first terminal of the antenna; a first switch connected in parallel with the single first capacitor; a single second variable resistor and a single second capacitor connected in series between the second terminal of the differential amplifier and the second terminal of the antenna; a second switch connected in parallel with the single second capacitor; and a controller, coupled to the first and second switches, and configured to; adjust a transmission bandwidth of the antenna, based on a data rate of data to be transmitted from the NFC reader, by short-circuiting the single first and second capacitors using the first and second switches, respectively. - View Dependent Claims (14, 15)
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16. A near field communications (NFC) reader, comprising:
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a first adjustable filter coupled between a first terminal of an antenna and a first terminal of a differential amplifier, the first adjustable filter comprising; a first variable resistor and a first capacitor connected in series between the first terminal of the differential amplifier and the first terminal of the antenna; and a first switch connected in parallel with the first capacitor; a second adjustable filter coupled between a second terminal of the antenna and a second terminal of the differential amplifier, the second adjustable filter comprising; a second variable resistor and a second capacitor connected in series between the second terminal of the differential amplifier and the second terminal of the antenna; and a second switch connected in parallel with the second capacitor; and a controller, coupled to the first and second adjustable filters, configured to adjust a transmission bandwidth of data to be transmitted from the NFC reader by short-circuiting the first and second capacitors using the first and second switches, respectively. - View Dependent Claims (17, 18, 19, 20)
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Specification