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US 8,994,472 B2Granted
Antenna duplexer
AssigneePanasonic Corporation
InventorsToru Yamaji, Kazunori Nishimura, Joji Fujiwara, Hiroyuki Nakamura
Life of this patent
Estimating the term…
Abstract
An antenna duplexer includes first and second filters connected to an antenna terminal. The first filter has a passband of a low frequency band. The second filter has a passband of a high frequency band. The second filter is a ladder-type filter including series-arm resonators and parallel-arm resonators. At least one parallel-arm resonator out of the parallel-arm resonators has a main resonance and an auxiliary resonance. Attenuation poles caused by the main resonance and the auxiliary resonance are within the low frequency band. This antenna duplexer has a high attenuation characteristic and a high isolation characteristic while maintaining a low insertion loss.
Claims20
An antenna duplexer comprising:
- an antenna terminal configured to be connected to an antenna;
- a first terminal configured to be connected to a first external circuit;
- a second terminal configured to be connected to a second external circuit;
- a first filter connected in series between the antenna terminal and the first terminal, the first filter having a passband in a low frequency band;
- and
- a second filter connected in series between the antenna terminal and the second terminal, the second filter having a passband in a high frequency band having a lowest frequency higher than a highest frequency of the low frequency band, the second filter including a plurality of series-arm resonators connected in series between the antenna terminal and the second terminal, and a plurality of parallel-arm resonators connected between a ground and the plurality of series-arm resonators to form a ladder-type filter together with the plurality of series-arm resonators, the plurality of parallel-arm resonators of the second filter including a first parallel-arm resonator connected at a position closest to the antenna terminal among the plurality of parallel-arm resonators, and a plurality of second parallel-arm resonators connected at positions farther from the antenna terminal than the first parallel-arm resonator, at least one second parallel-arm resonator out of the plurality of second parallel-arm resonators having a main resonance and a first auxiliary resonance, attenuation poles caused by the main resonance and the first auxiliary resonance being within the low frequency band.
3 more elements
An antenna duplexer comprising:
- an antenna terminal;
- a first filter connected in series between the antenna terminal and an input terminal, the first filter having a first passband in a first frequency band;
- and
- a second filter connected in series with the first filter between the input terminal and an output terminal, the antenna terminal being positioned between the first and second filters, the second filter having a second passband in a second frequency band higher than the first frequency band, the first and second frequency bands being non-overlapping, the second filter including a plurality of series-arm resonators connected in series between the antenna terminal and the output terminal to form a series arm of the second filter, and a plurality of parallel-arm resonators connected interspersed with the plurality of series-arm resonators between a ground and the series arm, the plurality of parallel-arm resonators including a first parallel-arm resonator connected at a position farthest from the antenna terminal among the plurality of parallel-arm resonators, and at least one second parallel-arm resonator connected at positions closer to the antenna terminal than the first parallel-arm resonator, a first second parallel-arm resonator of the at least one second parallel-arm resonator having a main resonance and a first auxiliary resonance that produce attenuation poles within the first frequency band.
1 more element
A communications device comprising:
- an antenna;
- a first filter having a first passband in a first frequency band;
- a transmission circuit configured to input a transmission signal to the antenna via the first filter, the first filter being connected in series between the transmission circuit and the antenna, the transmission signal having a frequency within the first frequency band;
- a reception circuit configured to receive a reception signal from the antenna;
- and
- a second filter having a second passband in a second frequency band having a lowest frequency higher than a highest frequency of the first frequency band, the second filter being connected in series between the antenna and the reception circuit and configured to pass the reception signal from the antenna to the reception circuit, the reception signal having a frequency within the second frequency band, the second filter including a plurality of series-arm resonators connected in series between the antenna and the reception circuit to form a series arm of the second filter, and a plurality of parallel-arm resonators connected interspersed with the plurality of series-arm resonators between a ground and the series-arm, the plurality of parallel-arm resonators of the second filter including a first parallel-arm resonator connected at a position closest to the antenna terminal among the plurality of parallel-arm resonators, and a plurality of second parallel-arm resonators connected at positions farther from the antenna terminal than the first parallel-arm resonator, at least one second parallel-arm resonator out of the plurality of second parallel-arm resonators having a main resonance and a first auxiliary resonance that produce attenuation poles within the first frequency band.
3 more elements
Dependencies are inferred from the claim text.