TRANSMIT AND RECEIVE PERFORMANCE OF A NEAR FIELD COMMUNICATION DEVICE THAT USES A SINGLE ANTENNA
First Claim
1. A circuit comprising:
- an antenna interface to couple to an antenna designed to communicate with external antennas by inductive coupling;
a transmitter portion to generate a transmit wireless signal to be transmitted by the antenna;
a shunt capacitor;
a receiver portion to receive and process a receive wireless signal from the antenna; and
a switch operable in a first mode and a second mode, wherein the switch couples the shunt capacitor in parallel with the antenna in the second mode,the switch decoupling the shunt capacitor from the antenna in the first mode.
1 Assignment
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Accused Products
Abstract
A near field communication (NFC) transceiver contains a transmitter portion to generate a transmit wireless signal, and a receiver portion to receive and process a receive wireless signal. The circuit further contains a shunt capacitor, a switch, and an antenna interface to couple the transmitter portion and the receiver portion to an antenna designed to communicate with external antennas by inductive coupling. The switch couples the shunt capacitor in parallel with the antenna in one operational mode, and decouples the shunt capacitor from the antenna in another operational mode. Transmit and receive performance of the NFC transceiver are enhanced as a result.
19 Citations
10 Claims
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1. A circuit comprising:
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an antenna interface to couple to an antenna designed to communicate with external antennas by inductive coupling; a transmitter portion to generate a transmit wireless signal to be transmitted by the antenna; a shunt capacitor; a receiver portion to receive and process a receive wireless signal from the antenna; and a switch operable in a first mode and a second mode, wherein the switch couples the shunt capacitor in parallel with the antenna in the second mode, the switch decoupling the shunt capacitor from the antenna in the first mode. - View Dependent Claims (2, 3, 4, 5)
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6. A device comprising:
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an application block to provide one or more user applications based on transmission and reception of near field communications (NFC) signals; an NFC transceiver; and
an antenna designed to communicate with external antennas by inductive coupling, wherein the NFC transceiver comprises;an antenna interface to couple to the antenna; a transmitter portion to generate a transmit wireless signal to be transmitted by the antenna; a shunt capacitor; a receiver portion to receive and process a receive wireless signal from the antenna; and a switch operable in a first mode and a second mode, wherein the switch couples the shunt capacitor in parallel with the antenna in the second mode, the switch decoupling the shunt capacitor from the antenna in the first mode. - View Dependent Claims (7, 8, 9)
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10. A near field communication (NFC) transceiver comprising:
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a baseband processor to generate a transmit baseband NFC signal, the baseband processor also to process a receive baseband NFC signal; an up-converter to convert the transmit baseband NFC signal to a frequency band specified by the NFC standard to generate a transmit NFC signal; a power amplifier to receive the transmit NFC signal and to generate a power-amplified NFC signal on a first pair of differential paths; a low noise amplifier (LNA) to receive an NFC receive signal on a second pair of differential paths, and to generate an amplified receive NFC signal; a down-converter to convert the amplified receive NFC signal from a frequency band specified by the NFC standard to generate the receive baseband NFC signal; and an antenna interface, wherein the antenna interface comprises; a first transistor and a second transistor, the control terminals of each of the first transistor and the second transistor being coupled to the baseband processor, wherein a first current terminal of each of the first transistor and the second transistor is coupled to a reference potential; a first shunt capacitor, wherein a first terminal of the first shunt capacitor is coupled to a first one of the paths in the first pair of differential paths, wherein a second terminal of the first shunt capacitor is coupled to a second current terminal of the first transistor; a second shunt capacitor, wherein a first terminal of the second shunt capacitor is coupled to a second one of the paths in the first pair of differential paths, the second terminal of the second shunt capacitor being coupled to a second current terminal of the second transistor; a third capacitor, wherein a first terminal of the third capacitor is coupled to the first one of the paths in the first pair of differential paths; a first resistor, a first terminal of the first resistor coupled to a second terminal of the third capacitor, a second terminal of the first resistor to couple to a first terminal of an NFC antenna; a second resistor, a first terminal of the second resistor to couple to a second terminal of the NFC antenna; a fourth capacitor, a first terminal of the fourth capacitor coupled to the second one of the paths in the first pair of differential paths, a second terminal of the fourth capacitor coupled to a second terminal of the second resistor; a fifth capacitor, a first terminal of the fifth capacitor coupled to a first one of the paths in the second pair of differential paths, a second terminal of the fifth capacitor coupled to the second terminal of the third capacitor; and a sixth capacitor, a first terminal of the sixth capacitor coupled to a second one of the paths in the second pair of differential paths, a second terminal of the sixth capacitor coupled to the second terminal of the fourth capacitor.
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Specification