Elastic wave device, duplexer using the same, and communication apparatus using the duplexer

Abstract

An elastic wave device includes resonators having a piezoelectric substrate, a resonation unit formed on the piezoelectric substrate, and reflectors formed on respective sides of the resonation unit on the piezoelectric substrate, and bumps formed on the piezoelectric substrate. The resonators are configured such that two or more split resonators are connected in parallel, and a bump is formed in a region sandwiched between reflectors of the split resonators.

The invention claimed is: 
     
       1. An elastic wave device comprising:
 a resonator having a piezoelectric substrate, a resonation unit formed on the piezoelectric substrate, and reflectors formed on respective sides of the resonation unit on the piezoelectric substrate; and 
 a bump formed on the piezoelectric substrate, 
 wherein the resonator is configured such that two or more split resonators are connected in parallel, and the bump is formed in a region sandwiched between reflectors of the split resonators and is electrically and acoustically separated from the resonator. 
 
     
     
       2. The elastic wave device according to  claim 1 , having signal wiring connected to the resonation unit,
 wherein the bump is surrounded by the signal wiring and the reflectors. 
 
     
     
       3. The elastic wave device according to  claim 1 , wherein the bump is connected to a ground. 
     
     
       4. The elastic wave device according to  claim 1 , wherein the bump is connected to external wiring. 
     
     
       5. The elastic wave device according to  claim 1 , wherein the split resonators each have the same number of pairs of comb-shaped electrodes. 
     
     
       6. The elastic wave device according to  claim 1 , wherein in each of the split resonators, comb-shaped electrodes are formed using the same design. 
     
     
       7. The elastic wave device according to  claim 1 , wherein a material of the bump is Au. 
     
     
       8. A filter comprising the elastic wave device according to  claim 1 , wherein the elastic wave device includes a plurality of resonators, and the plurality of resonators are connected to each other. 
     
     
       9. A duplexer comprising:
 a transmission filter; and 
 a reception filter having a pass frequency band different from that of the transmission filter, 
 wherein at least one of the transmission filter and the reception filter is configured using the filter according to  claim 8 . 
 
     
     
       10. A communication apparatus comprising:
 an antenna; 
 the duplexer according to  claim 9  that is connected to the antenna; and a signal processing unit connected to the duplexer. 
 
     
     
       11. The elastic wave device according to claim 1, wherein there is no bump other than said bump in said region sandwiched between the reflectors of the split resonators. 
     
     
       12. An elastic wave device comprising:
 a resonator configured to have two or more split resonators formed on a piezoelectric substrate; and   a bump formed on the piezoelectric substrate,   wherein said two or more split resonators are connected in parallel, and the bump is formed in a region sandwiched between the split resonators and is electrically and acoustically separated from the split resonators.   
     
     
       13. The elastic wave device according to claim 12, wherein the bump is connected to a ground. 
     
     
       14. A filter comprising the elastic wave device according to claim 12, wherein the elastic wave device includes a plurality of resonators connected to each other. 
     
     
       15. A duplexer comprising:
 a transmission filter; and   a reception filter having a pass frequency band different from that of the transmission filter,   wherein at least one of the transmission filter and the reception filter is the filter according to claim 14.   
     
     
       16. The elastic wave device according to claim 12, wherein there is no bump other than said bump in said region sandwiched between the split resonators. 
     
     
       17. An elastic wave device comprising:
 a resonator configured to have two or more split resonators, the split resonators each having a resonation unit formed on a piezoelectric substrate and reflectors formed on respective sides of the resonation unit on the piezoelectric substrate; and   a bump formed on the piezoelectric substrate,   wherein said two or more split resonators are connected in parallel, and the bump is formed in a region sandwiched between reflectors of the split resonators and is electrically and acoustically separated from the resonation unit of the respective split resonators.   
     
     
       18. The elastic wave device according to claim 17, wherein the bump is connected to a ground. 
     
     
       19. A filter comprising the elastic wave device according to claim 17, wherein the elastic wave device includes a plurality of resonators connected to each other. 
     
     
       20. A duplexer comprising:
 a transmission filter; and   a reception filter having a pass frequency band different from that of the transmission filter,   wherein at least one of the transmission filter and the reception filter is the filter according to claim 19.   
     
     
       21. The elastic wave device according to claim 17, wherein there is no bump other than said bump in said region sandwiched between the reflectors of the split resonators. 
     
     
       22. An elastic wave device comprising:
 a plurality of resonators on a piezoelectric substrate, the plurality of resonators including two or more split resonators each having a pair of comb-shaped electrodes; and   a bump formed on the piezoelectric substrate,   wherein said two or more split resonators are connected in parallel, and the bump is formed in a region sandwiched between the split resonators and is electrically and acoustically separated from said comb-shaped electrodes of the split resonators.   
     
     
       23. The elastic wave device according to claim 22, wherein the bump is connected to a ground. 
     
     
       24. A filter comprising the elastic wave device according to claim 22, wherein the elastic wave device includes a plurality of resonators connected to each other. 
     
     
       25. A duplexer comprising:
 a transmission filter; and   a reception filter having a pass frequency band different from that of the transmission filter,   wherein at least one of the transmission filter and the reception filter is the filter according to claim 24.   
     
     
       26. The elastic wave device according to claim 22, wherein there is no bump other than said bump in said region sandwiched between the split resonators. 
     
     
       27. An elastic wave device comprising:
 a plurality of resonators on a piezoelectric substrate, the plurality of resonators each having a pair of comb-shaped electrodes, the plurality of resonators including two or more split resonators each having a pair of comb-shaped electrodes; and   a bump formed on the piezoelectric substrate,   wherein said two or more split resonators are connected in parallel, and the bump is formed in a region sandwiched between the split resonators and is electrically and acoustically separated from said comb-shaped electrodes of any of the resonators that are adjacent to the bump.   
     
     
       28. The elastic wave device according to claim 27, wherein the bump is connected to a ground. 
     
     
       29. A filter comprising the elastic wave device according to claim 27, wherein the elastic wave device includes a plurality of resonators connected to each other. 
     
     
       30. A duplexer comprising:
 a transmission filter; and   a reception filter having a pass frequency band different from that of the transmission filter,   wherein at least one of the transmission filter and the reception filter is the filter according to claim 29.   
     
     
       31. The elastic wave device according to claim 27, wherein there is no bump other than said bump in said region sandwiched between the split resonators. 
     
     
       32. An elastic wave device comprising:
 a resonator having first and second signal wiring patterns on a surface of a piezoelectric substrate, the resonator having two split resonators arranged side-by-side with each other on the surface of the piezoelectric substrate, the two split resonators being disposed between, and each connected to, the first and second signal wiring patterns so as to be connected in parallel with each other between the first and second signal wiring patterns; and   a bump formed on a metal island on the surface of the piezoelectric substrate,   wherein the metal island having the bump thereon is disposed in a region on the surface of the piezoelectric substrate sandwiched between the two split resonators and surrounded by the first and second signal wiring patterns and the two split resonators, and is not connected to, and therefore is separated from, any of the two split resonators and the first and second signal wiring patterns on the surface of the piezoelectric substrate so that the bump on the metal island is electrically and acoustically separated from the two split resonators on the surface of the piezoelectric substrate.