Multiplexer with acoustic wave resonators

Abstract

Embodiments of this disclosure relate to multiplexers that include acoustic wave filters for filtering radio frequency signals. In certain embodiments, a multiplexer includes a first acoustic wave filter including bulk acoustic wave resonators and a second acoustic wave filter including multilayer piezoelectric substrate surface acoustic wave resonators. The second acoustic wave filter can have a second pass band that is above a first pass band of the first acoustic wave filter. Related acoustic filter assemblies, packaged radio frequency modules, wireless communication devices, and methods are disclosed.

What is claimed is: 
     
         1 . A multiplexer with acoustic wave filters for filtering radio frequency signals, the multiplexer comprising:
 a first acoustic wave filter coupled to a common node and having a first pass band, the first acoustic wave filter including bulk acoustic wave resonators;   a second acoustic wave filter coupled to the common node and having a second pass band;   a third acoustic wave filter coupled to the common node and having a third pass band; and   a fourth acoustic wave filter coupled to the common node and having a fourth pass band, the fourth acoustic wave filter including surface acoustic wave resonators, the first pass band having a lower pass band than the second, third and fourth acoustic wave filters.   
     
     
         2 . The multiplexer of  claim 1  wherein the fourth pass band is a highest pass band of the first, second and third acoustic wave filters. 
     
     
         3 . The multiplexer of  claim 1  wherein the surface acoustic wave resonators include multilayer piezoelectric substrate surface acoustic wave resonators. 
     
     
         4 . The multiplexer of  claim 1  wherein the first acoustic wave filter and third acoustic wave filter each include multilayer piezoelectric substrate surface acoustic wave resonators. 
     
     
         5 . The multiplexer of  claim 1  wherein the surface acoustic wave resonators include temperature compensated surface acoustic wave resonators. 
     
     
         6 . The multiplexer of  claim 1  wherein the second acoustic wave filter includes second bulk acoustic wave resonators, the third acoustic wave filter includes second surface acoustic wave resonators, and the second pass band being below the third pass band. 
     
     
         7 . The multiplexer of  claim 1  wherein the second acoustic wave filter includes second bulk acoustic wave resonators, the third acoustic wave filter includes third bulk acoustic wave resonators, and the second pass band is below the third pass band. 
     
     
         8 . The multiplexer of  claim 1  wherein the second acoustic wave filter includes second surface acoustic wave resonators, the third acoustic wave filter includes third surface acoustic wave resonators, and the second pass band is below the third pass band. 
     
     
         9 . The multiplexer of  claim 1  wherein the multiplexer is configured to support a carrier aggregation of at least two frequency bands. 
     
     
         10 . The multiplexer of  claim 1  wherein the multiplexer is configured to support a carrier aggregation of at least three frequency bands. 
     
     
         11 . The multiplexer of  claim 1  wherein the bulk acoustic wave resonators have spurious modes below the first pass band. 
     
     
         12 . The multiplexer of  claim 1  wherein the surface acoustic wave resonators have a gamma of at least 0.85 in the first pass band. 
     
     
         13 . The multiplexer of  claim 1  wherein spurious modes of the bulk acoustic wave resonators are outside of the fourth pass band. 
     
     
         14 . The multiplexer of  claim 1  wherein the bulk acoustic wave resonators have a substantially constant gamma in the fourth pass band. 
     
     
         15 . A wireless communication device comprising:
 an antenna; and   a radio frequency front end including a multiplexer in communication with the antenna, the multiplexer including:   a first acoustic wave filter coupled to a common node and having a first pass band, the first acoustic wave filter including bulk acoustic wave resonators;   a second acoustic wave filter coupled to the common node and having a second pass band;   a third acoustic wave filter coupled to the common node and having a third pass band; and   a fourth acoustic wave filter coupled to the common node and having a fourth pass band, the fourth acoustic wave filter including surface acoustic wave resonators, the first pass band having a lower pass band than the second, third and fourth acoustic wave filters.   
     
     
         16 . The wireless communication device of  claim 15  wherein the radio frequency front end includes a frequency multiplexing circuit coupled between the common node of the multiplexer and the antenna. 
     
     
         17 . The wireless communication device of  claim 15  further comprising an antenna switch coupled between the common node of the multiplexer and the antenna. 
     
     
         18 . A packaged radio frequency module comprising:
 a multiplexer including:
 a first acoustic wave filter coupled to a common node and having a first pass band, the first acoustic wave filter including bulk acoustic wave resonators; 
 a second acoustic wave filter coupled to the common node and having a second pass band; 
 a third acoustic wave filter coupled to the common node and having a third pass band; and 
 a fourth acoustic wave filter coupled to the common node and having a fourth pass band, the fourth acoustic wave filter including surface acoustic wave resonators, the first pass band having a lower pass band than the second, third and fourth acoustic wave filters; 
   a multi-throw radio frequency switch coupled to the multiplexer; and   a package enclosing the multiplexer and the multi-throw radio frequency switch.   
     
     
         19 . The packaged radio frequency module of  claim 18  further comprising a power amplifier enclosed within the package, the power amplifier configured to provide a radio frequency signal to the multiplexer. 
     
     
         20 . The packaged radio frequency module of  claim 18  further comprising a low noise amplifier enclosed within the package, the low noise amplifier configured to receive a radio frequency signal to the multiplexer.