US Patent 7446628 Pole-zero elements and related systems and methods

According to one aspect, the subject matter described herein includes a tunable duplexer. The tunable duplexer can include a common node for communicating signals comprising a plurality of frequencies. Further, the tunable duplexer can include first and second band nodes for communicating first and second predetermined frequency bands, respectively, of the plurality of frequencies. The tunable duplexer can also include a filter coupled between the common node and the first and second band nodes. The filter can include pole-zero elements adapted to pass signals of the first and second predetermined frequency bands to the first and second band nodes, respectively. Further, the filter can be adapted to block signals of the first and second predetermined frequency band to the second and first band nodes, respectively.