DUPLEXER AND ELECTRONIC DEVICE

• US 20110254639A1
• Filed: 06/23/2011
• Published: 10/20/2011
• Est. Priority Date: 12/26/2008
• Status: Active Grant

• Current Assignee: Taiyo Yuden Company Limited (Taiyo Yuden Co)
• Original Assignee: Taiyo Yuden Company Limited (Taiyo Yuden Co)
• Inventors: MATSUMOTO, Kazuhiro, INOUE, Shogo, TSUTSUMI, Jun
• Granted Patent: US 8,274,342 B2
• Time in Patent Office: Days
• US Class Current: 333/132
• CPC Class Codes: H01P 1/213 combining or separating two or more different frequencies H01P1/215 takes precedence
• CPC Class Codes: H03H 9/0571 including bulk acoustic wave [BAW] devices
• CPC Class Codes: H03H 9/0576 including surface acoustic wave [SAW] devices
• 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 9/725 Duplexers

Abstract

A ladder type filter includes series resonators connected in series between an input terminal and an output terminal, parallel resonators connected in parallel between the input terminal and the output terminal, a resonator connected in series with the series resonators between the input terminal and the output terminal, the resonator having a resonance frequency lower than resonance frequencies of the series resonators, and an inductor connected in parallel with the resonator. According to the present ladder filter, signals having frequencies away from the pass band can be suppressed by an attenuation pole formed by the inductor. it is further possible to suppress the insertion loss in the pass band by the resonator.

Claims

1. A duplexer comprising:

a transmission filter connected between a common terminal and a transmission terminal;

a reception filter connected between the common terminal and a reception filter; and

a capacitor connected in parallel with one of the transmission filter and the reception filter between at least two terminals out of the common terminal, the transmission terminal and the reception terminal.

2. The duplexer according to claim 1, wherein a plurality of capacitors each being said capacitor are connected in series.

3. The duplexer according to claim 1, further comprising a package on which the transmission filter and the reception filter are mounted, the package including the capacitor.

4. The duplexer according to claim 3, wherein the capacitor is formed by two lines formed on an identical surface of an insulation layer within the package.

5. The duplexer according to claim 3, further comprising a microstrip line formed on a surface of an insulation layer within the package,

the plurality of capacitors being respectively connected to two of the common terminal, the transmission terminal and the reception terminal, and being formed by lines formed on the surface of the insulation layer and both ends of the microstrip

6. The duplexer according to claim 1, wherein the capacitor is connected between the transmission terminal and the reception terminal.

7. An electronic device comprising:

a duplexer;

a transmission circuit connected to the duplexer; and

a reception circuit connected to the duplexer,

the duplexer including;

a transmission filter connected between a common terminal and a transmission terminal connected to the transmission circuit;

a reception filter connected between the common terminal and a reception terminal connected to the reception circuit; and

a capacitor connected in parallel with one of the transmission filter and the reception filter between at least two terminals out of the common terminal, the transmission terminal and the reception terminal.