DUPLEXER, FILTER AND COMMUNICATION MODULE

• US 20130113576A1
• Filed: 09/05/2012
• Published: 05/09/2013
• Est. Priority Date: 11/04/2011
• Status: Active Grant

• Current Assignee: Taiyo Yuden Company Limited (Taiyo Yuden Co)
• Original Assignee: Taiyo Yuden Company Limited (Taiyo Yuden Co)
• Inventors: Inoue, Shogo, Iwaki, Masafumi, Tsutsumi, Jun
• Granted Patent: US 9,219,467 B2
• Time in Patent Office: Days
• US Class Current: 333/133
• CPC Class Codes: H03H 9/54 comprising resonators of piezoelectric or electrostrictive material H03H9/64 takes precedence
• CPC Class Codes: H03H 9/6433 Coupled resonator filters
• CPC Class Codes: H03H 9/70 Multiple-port networks for connecting several sources or loads, working on different frequencies or frequency bands, to a common load or source
• CPC Class Codes: H03H 9/706 Duplexers
• CPC Class Codes: H03H 9/725 Duplexers

Abstract

A duplexer includes: a transmit filter that is connected between an antenna terminal and a transmit terminal and has a plurality of acoustic wave resonators; a receive filter that is connected between the antenna terminal and a receive terminal and has a plurality of acoustic wave resonators; and a delay line or a longitudinal coupling type resonator that is connected in parallel with at least one of the plurality of acoustic wave resonators of the transmit filter and the plurality of acoustic wave resonators of the receive filter and has at least two IDTs (Interdigital Transducers).

Claims

1. A duplexer comprising:

a transmit filter that is connected between an antenna terminal and a transmit terminal and has a plurality of acoustic wave resonators;

a receive filter that is connected between the antenna terminal and a receive terminal and has a plurality of acoustic wave resonators; and

a delay line or a longitudinal coupling type resonator that is connected in parallel with at least one of the plurality of acoustic wave resonators of the transmit filter and the plurality of acoustic wave resonators of the receive filter and has at least two IDTs (Interdigital Transducers).

2. The duplexer as claimed in claim 1 further comprising a first acoustic wave resonator that is provided at least one of on an input side and on an output side of the delay line or the longitudinal coupling type resonator and is connected in series with the delay line or the longitudinal coupling type acoustic wave resonator,

wherein:

one of the transmit filter and the receive filter having a pass band frequency lower than that of the other is a ladder type filter; and

an anti-resonance frequency of the first acoustic wave resonator is in a pass band of one of the transmit filter and the receive filter having a pass band frequency higher than that of the other.

3. The duplexer as claimed in claim 1 further comprising a second acoustic wave resonator that is provided at least one of on an input side and on an output side of the delay line or the longitudinal coupling type resonator and is connected in parallel with the delay line or the longitudinal coupling type acoustic wave resonator,

wherein:

one of the transmit filter and the receive filter having a pass band frequency higher than that of the other is a ladder type filter; and

a resonance frequency of the second acoustic wave resonator is in a pass band of one of the transmit filter and the receive filter having a pass band frequency lower than that of the other.

4. The duplexer as claimed in claim 1 further comprising an acoustic wave resonator or an electrostatic capacitor that is provided at least one of on an input side and on an output side of the delay line or the longitudinal coupling type resonator and is connected in series with the delay line or the longitudinal coupling type resonator.

5. The duplexer as claimed in claim 4 wherein the acoustic wave resonator or the electrostatic capacitor is provided both of on the input side and on the output side of the delay line or the longitudinal coupling type resonator and is connected in series with the delay line or the longitudinal coupling type resonator.

6. The duplexer as claimed in claim 4 further comprising an acoustic wave resonator or an electrostatic capacitor connected in parallel with the delay line or the longitudinal coupling type resonator between a node between the delay line or the longitudinal coupling type resonator and the acoustic wave resonator or the electrostatic capacitor connected in series and a ground.

7. The duplexer as claimed in claim 1, wherein the longitudinal coupling type resonator has three IDTs.

8. The duplexer as claimed in claim 1, wherein the delay line or the longitudinal coupling type resonator is connected between the transmit terminal and the receive terminal in parallel with the transmit filter and the receive filter.

9. The duplexer as claimed in claim 1, wherein the delay line or the longitudinal coupling type resonator is connected between the transmit terminal and the antenna terminal in parallel with the transmit filter.

10. The duplexer as claimed in claim 1, wherein the delay line or the longitudinal coupling type resonator is connected between the receive terminal and the antenna terminal in parallel with the receive filter.

11. The duplexer as claimed in claim 1, wherein a plurality of the delay lines or the longitudinal coupling type resonators are provided.

12. The duplexer as claimed in claim 4, wherein the electrostatic capacitor connected in series is structured by an IDT without a reflector.

13. The duplexer as claimed in claim 6, wherein the electrostatic capacitor connected in parallel is structured by an IDT without a reflector.

14. The duplexer as claimed in claim 6, wherein at least one of or all of either the delay line or the longitudinal coupling type resonator, either the acoustic wave resonator or the electrostatic capacitor connected in series, and either the acoustic wave resonator or the electrostatic capacitor connected in parallel is provided on a transmit filter chip and a receive filter chip.

15. The duplexer as claimed in claim 5, wherein:

an acoustic wave resonator or an electrostatic capacitor of the acoustic wave resonators or the electrostatic capacitors connected in series provided on the side of the transmit terminal is provided on a transmit filter chip;

an acoustic wave resonator or an electrostatic capacitor of the acoustic wave resonators or the electrostatic capacitors connected in series provided on the side of the receive terminal is provided on a receive filter chip; and

the delay line or the longitudinal coupling type resonator is provided on the transmit filter chip or the receive filter chip.

16. The duplexer as claimed in claim 4, wherein:

the transmit filter and the receive filter are a filter including a series resonator; and

a relation “

λ

_IDT>

1.138×

λ

_cap”

is obtained when a pitch of electrode fingers of a series resonator having the largest pitch of electrode fingers in the series resonators connected in parallel with the delay line or the longitudinal coupling type resonator included in one of the transmit filter and the receive filter having a pass band frequency higher than that of the other is “

λ

_IDT”

, and a pitch of electrode fingers of the acoustic wave resonator connected in series is “

λ

_cap”

.

22. A communication module comprising:

the duplexer as claimed in claim 1.

17. A filter comprising:

a plurality of acoustic wave resonators connected between an input terminal and an output terminal; and

a delay line or a longitudinal coupling type resonator that is connected in parallel with at least one of the plurality of acoustic wave resonators and has at least two IDTs (Interdigital Transducers).

18. The filter as claimed in claim 17 further comprising a first acoustic wave resonator that is provided at least one of on an input side and on an output side of the delay line or the longitudinal coupling type resonator and is connected in series with the delay line or the longitudinal coupling type resonator,

wherein:

the plurality of acoustic wave resonators connected between the input terminal and the output terminal structure a ladder type filter; and

an anti-resonance frequency of the first acoustic wave resonator is in a suppressed band on a higher frequency side of the ladder type filter.

19. The filter as claimed in claim 17 further comprising a second acoustic wave resonator that is provided at least one of on an input side and on an output side of the delay line or the longitudinal coupling type resonator and is connected in parallel with the delay line or the longitudinal coupling type resonator,

wherein:

the plurality of acoustic wave resonators connected between the input terminal and the output terminal structure a ladder type filter; and

a resonance frequency of the second acoustic wave resonator is in a suppressed band on a lower frequency side of the ladder type filter.

20. The filter as claimed in claim 17 further comprising an acoustic wave resonator or an electrostatic capacitor that is provided at least one of on an input side and on an output side of the delay line or the longitudinal coupling type resonator and is connected in series with the delay line or the longitudinal coupling type resonator.

21. The filter as claimed in claim 20 further comprising an acoustic wave resonator or an electrostatic capacitor connected in parallel with the delay line or the longitudinal coupling type resonator between a node between the delay line or the longitudinal coupling type resonator and the acoustic wave resonator or the electrostatic capacitor connected in series and a ground.