Multiplexers as a method of supporting same-frequency-range down link carrier aggregation

Carrier aggregation increases the requirements on filtering in LTE-A handsets. In particular, aggregation of two or more bands relatively close in frequency range can pose difficult problems. Multiplexers, filter structures sharing a common antenna port and supporting the filtering needs of multiple bands, are a possible answer. Bulk wave filtering in particular has the necessary performance characteristics needed to construct multiplexers. This paper analyzes the increased filtering needs encountered in same-frequency-range down link carrier aggregation, and presents some multiplexer structures that can meet those needs.