Duplexer and method of manufacturing same

1. A duplexer comprising a transmission filter for passing a transmission signal therethrough and interrupting a reception signal and a reception filter for passing a reception signal therethrough and interrupting a transmission signal, the duplexer being connected to an antenna, wherein:

the duplexer further comprises a base;

each of the transmission filter and the reception filter includes thin-film piezoelectric resonators each of which has a piezoelectric thin film that exhibits a piezoelectric property and first and second excitation electrodes that are disposed on both surfaces of the piezoelectric thin film and apply an excitation voltage to the piezoelectric thin film;

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include are disposed on the base;

the piezoelectric thin films of all of the thin-film piezoelectric resonators are continuous;

the transmission filter includes a first series resonator and a first parallel resonator that constitute a ladder-type filter circuit, each of the first series resonator and the first parallel resonator being made up of one of the thin-film piezoelectric resonators;

the reception filter includes a second series resonator and a second parallel resonator that constitute a ladder-type filter circuit, each of the second series resonator and the second parallel resonator being made up of one of the thin-film piezoelectric resonators;

in the transmission filter, the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator each disposed on one of the surfaces of the piezoelectric thin film have different thicknesses;

in the reception filter, the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator each disposed on one of the surfaces of the piezoelectric thin film have different thicknesses; and

the difference in thickness between the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator is equal to the difference in thickness between the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator.

2. The duplexer according to claim 1 , wherein the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator having the different thicknesses are both disposed on the one of the surfaces of the piezoelectric thin film that is farther from the base, and the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator having the different thicknesses are both disposed on the one of the surfaces of the piezoelectric thin film that is farther from the base.

3. The duplexer according to claim 1 , wherein, among the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator having the different thicknesses and the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator having the different thicknesses, the excitation electrode of the first series resonator is made up of a first electrode film having a first thickness, the excitation electrode of the second series resonator is made up of a second electrode film having a second thickness, the excitation electrode of the first parallel resonator is made up of a layered structure of the first electrode film and a third electrode film, and the excitation electrode of the second parallel resonator is made up of a layered structure of the second electrode film and the third electrode film.

4. A duplexer comprising a transmission filter for passing a transmission signal therethrough and interrupting a reception signal and a reception filter for passing a reception signal therethrough and interrupting a transmission signal, the duplexer being connected to an antenna, wherein:

the duplexer further comprises a base;

each of the transmission filter and the reception filter includes thin-film piezoelectric resonators each of which has a piezoelectric thin film that exhibits a piezoelectric property and first and second excitation electrodes that are disposed on both surfaces of the piezoelectric thin film and apply an excitation voltage to the piezoelectric thin film;

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include are disposed on the base;

the piezoelectric thin films of all of the thin-film piezoelectric resonators are continuous;

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include further have acoustic multi-layer films, each acoustic multi-layer film being made up of a plurality of dielectric layers having different acoustic impedances; and

the acoustic multi-layer films of all of the thin-film piezoelectric resonators have the same thicknesses.

5. A duplexer comprising a transmission filter for passing a transmission signal therethrough and interrupting a reception signal and a reception filter for passing a reception signal therethrough and interrupting a transmission signal, the duplexer being connected to an antenna, wherein:

the duplexer further comprises a base;

each of the transmission filter and the reception filter includes thin-film piezoelectric resonators each of which has a piezoelectric thin film that exhibits a piezoelectric property and first and second excitation electrodes that are disposed on both surfaces of the piezoelectric thin film and apply an excitation voltage to the piezoelectric thin film;

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include are disposed on the base;

the piezoelectric thin films of all of the thin-film piezoelectric resonators are continuous;

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include further have acoustic multi-layer films, each acoustic multi-layer film being made up of a plurality of dielectric layers having different acoustic impedances; and

the acoustic multi-layer films of all of the thin-film piezoelectric resonators are continuous.

6. A method of manufacturing a duplexer comprising a transmission filter for passing a transmission signal therethrough and interrupting a reception signal and a reception filter for passing a reception signal therethrough and interrupting a transmission signal, the duplexer being connected to an antenna, wherein each of the transmission filter and the reception filter includes thin-film piezoelectric resonators each of which has a piezoelectric thin film that exhibits a piezoelectric property and first and second excitation electrodes that are disposed on both surfaces of the piezoelectric thin film and apply an excitation voltage to the piezoelectric thin film, the method comprising the steps of:

forming the first excitation electrodes of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on a single base;

forming the piezoelectric thin films on the first excitation electrodes so that the piezoelectric thin films of all of the thin-film piezoelectric resonators are made continuous; and

forming the second excitation electrodes of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on the piezoelectric thin films, wherein:

the transmission filter is made to include a first series resonator and a first parallel resonator that constitute a ladder-type filter circuit, each of the first series resonator and the first parallel resonator being made up of one of the thin-film piezoelectric resonators;

the reception filter is made to include a second series resonator and a second parallel resonator that constitute a ladder-type filter circuit, each of the second series resonator and the second parallel resonator being made up of one of the thin-film piezoelectric resonators;

in the transmission filter, the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator each disposed on one of the surfaces of the piezoelectric thin film are made to have different thicknesses;

in the reception filter, the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator each disposed on one of the surfaces of the piezoelectric thin film are made to have different thicknesses; and

the difference in thickness between the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator is made to be equal to the difference in thickness between the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator.

7. The method according to claim 6 , wherein the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator having the different thicknesses are both disposed on the one of the surfaces of the piezoelectric thin film that is farther from the base, and the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator having the different thicknesses are both disposed on the one of the surfaces of the piezoelectric thin film that is farther from the base.

8. The method according to claim 6 , wherein, among the excitation electrode of the first series resonator and the excitation electrode of the first parallel resonator having the different thicknesses and the excitation electrode of the second series resonator and the excitation electrode of the second parallel resonator having the different thicknesses, the excitation electrode of the first series resonator is made up of a first electrode film having a first thickness, the excitation electrode of the second series resonator is made up of a second electrode film having a second thickness, the excitation electrode of the first parallel resonator is made up of a layered structure of the first electrode film and a third electrode film, and the excitation electrode of the second parallel resonator is made up of a layered structure of the second electrode film and the third electrode film.

9. A method of manufacturing a duplexer comprising a transmission filter for passing a transmission signal therethrough and interrupting a reception signal and a reception filter for passing a reception signal therethrough and interrupting a transmission signal, the duplexer being connected to an antenna, wherein each of the transmission filter and the reception filter includes thin-film piezoelectric resonators each of which has a piezoelectric thin film that exhibits a piezoelectric property and first and second excitation electrodes that are disposed on both surfaces of the piezoelectric thin film and apply an excitation voltage to the piezoelectric thin film, the method comprising the steps of:

forming the first excitation electrodes of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on a single base;

forming the piezoelectric thin films on the first excitation electrodes so that the piezoelectric thin films of all of the thin-film piezoelectric resonators are made continuous; and

forming the second excitation electrodes of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on the piezoelectric thin films, wherein:

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include are made to further have acoustic multi-layer films, each acoustic multi-layer film being made up of a plurality of dielectric layers having different acoustic impedances;

the method further comprises the step of forming the acoustic multi-layer films of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on the base, the step being performed before the step of forming the first excitation electrodes;

the first excitation electrodes are formed on the acoustic multi-layer films; and

the acoustic multi-layer films of all of the thin-film piezoelectric resonators are made to have the same thicknesses.

10. A method of manufacturing a duplexer comprising a transmission filter for passing a transmission signal therethrough and interrupting a reception signal and a reception filter for passing a reception signal therethrough and interrupting a transmission signal, the duplexer being connected to an antenna, wherein each of the transmission filter and the reception filter includes thin-film piezoelectric resonators each of which has a piezoelectric thin film that exhibits a piezoelectric property and first and second excitation electrodes that are disposed on both surfaces of the piezoelectric thin film and apply an excitation voltage to the piezoelectric thin film, the method comprising the steps of:

forming the first excitation electrodes of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on a single base;

forming the piezoelectric thin films on the first excitation electrodes so that the piezoelectric thin films of all of the thin-film piezoelectric resonators are made continuous; and

forming the second excitation electrodes of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on the piezoelectric thin films, wherein:

all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include are made to further have acoustic multi-layer films, each acoustic multi-layer film being made up of a plurality of dielectric layers having different acoustic impedances;

the method further comprises the step of forming the acoustic multi-layer films of all of the thin-film piezoelectric resonators that the transmission filter and the reception filter include on the base, the step being performed before the step of forming the first excitation electrodes;

the first excitation electrodes are formed on the acoustic multi-layer films; and

the acoustic multi-layer films of all of the thin-film piezoelectric resonators are made to be continuous.