Design considerations for high power BAW duplexers for base station applications

Bulk Acoustic Wave (BAW) filters have become abundant in the handset market in recent years. These same filters can be implemented in the base station as well, although their electrical requirements differ from their mobile handset equivalent. Base stations are used to address cellular coverage in buildings and congested urban areas. They use a duplexer based architecture much like a mobile phone with transmit (Tx) and receive (Rx) paths, however the roles are reversed within a base station. Thus the Tx filter must handle higher power levels, provide higher reliability, and achieve higher isolation in the Rx band than the mobile counterpart. The purpose of this work is to leverage the BAW superior power handling and robustness attributes to address the small cell base station market. This market is currently serviced by cavity type filters which are large and expensive, but offer high performance and reliability. The market requires cost effective solutions without sacrificing performance. We believe that BAW technology could be competitive to cavity type filters in the small cell base station market.