Transceiving circuit for contactless communication and NFC device or RFID reader/writer device comprising such a transceiving circuit
View Patent ↗A transceiving circuit ( 1, 1 ′) for contactless communication comprises transmitter means ( 3 ) being adapted to generate an electromagnetic carrier signal and to modulate the carrier signal according to transmitting data, and an antenna ( 5 ) being connected to and driven by the transmitter means ( 3 ) with the modulated carrier signal. At least one impedance-matching capacitor (C 1 a ) is arranged serially to the antenna ( 5 ).
1. A transceiving circuit for contactless communication comprising:
transmitter means configured to generate an electromagnetic carrier signal and to modulate the carrier signal for transmitting data;
an antenna, wherein the antenna is connected to the transmitter means and driven by the transmitter means using the modulated carrier signal;
a first impedance-matching capacitor formed in a first transmission path that is coupled to a first output terminal of the transmitter means;
a second impedance-matching capacitor formed in a second transmission path that is coupled to a second output terminal of the transmitter means;
a tapping point of a receiving path that is coupled to the first transmission path so that the tapping point is interposed between the first output terminal and the first impedance-matching capacitor;
a phase adjusting capacitor that is switched into the receiving path; and
an electromagnetic compatibility filter that is connected between the first and second output terminals of the transmitter means and the first and second impedance-matching capacitors, wherein the first impedance-matching capacitor is interposed between the tapping point and the antenna, wherein the antenna comprises first and second capacitors and an inductor, wherein the first and second capacitors are connected together in series and the inductor is coupled between the first and second impedance matching capacitors in parallel with the first and second capacitors.
2. An electronic device comprising a transceiving circuit according to claim 1 .
3. The transceiving circuit defined in claim 1 , wherein the first output terminal of the transmitter means is coupled to a first side of the tapping point and the first impedance-matching capacitor is coupled to a second side of the tapping point that is different from the first side.
4. The transceiving circuit defined in claim 3 , wherein the antenna is coupled to the second side of the tapping point through the first impedance-matching capacitor.
5. The transceiving circuit defined in claim 4 , wherein the antenna is coupled to the second output terminal of the transmitter means through the second impedance-matching capacitor.
6. The transceiving circuit defined in claim 5 , wherein the first impedance-matching capacitor is coupled between the tapping point and a first side of the antenna and the second impedance-matching capacitor is coupled between the second output terminal of the transmitter means and a second side of the antenna that opposes the first side of the antenna.
7. The transceiving circuit defined in claim 6 , wherein the antenna comprises two capacitive elements and at least one inductive element.
8. The transceiving circuit defined in claim 1 , wherein the first and second capacitors are directly connected together in series.
9. The transceiving circuit defined in claim 8 , wherein the inductor is directly connected to the first and second capacitors.
10. A transceiving circuit for contactless communication comprising:
transmitter means configured to generate an electromagnetic carrier signal and to modulate the carrier signal for transmitting data; and
an antenna that is connected to and driven by the transmitter means using the modulated carrier signal, wherein first and second transmission paths are connected between the antenna and corresponding first and second output terminals of the transmitter means, wherein the antenna comprises first and second inductors and an impedance matching capacitor connected in series between the first and second inductors, wherein a tapping point of a receiving path is connected to the first transmission path at a location that is between the first output terminal and the first inductor of the antenna, and wherein the second inductor is connected in series between the impedance matching capacitor and the second transmission line path.
11. The transceiving circuit defined in claim 10 , wherein the first output terminal is coupled to the first inductor through the tapping point.
12. The transceiving circuit defined in claim 10 , further comprising filtering circuitry coupled to the first and second transmission paths between the antenna and the transmitter means.
13. The transceiving circuit defined in claim 10 , wherein the impedance matching capacitor is directly connected to the first and second inductors.
14. The transceiving circuit defined in claim 13 , further comprising a first capacitor connected in parallel with the first inductor between the impedance matching capacitor and the first transmission line path, wherein the first capacitor is directly connected to the impedance matching capacitor.
15. The transceiving circuit defined in claim 14 , further comprising a second capacitor connected in parallel with the second inductor between the impedance matching capacitor and the second transmission line path, wherein the second capacitor is directly connected to the impedance matching capacitor.