Novel Synthesis Technique of Mixed-Topology Extracted-Pole Resonators with Parallel-Connected Structures for Ladder-Type Acoustic Filters
This paper presents a novel contribution for mixed topologies synthesis methods with application to fully-canonical extracted-pole filters combining inline extractions with parallel-connected structures is introduced. This methodology has a great potential with filters based on acoustic wave resonators. Despite classical network synthesis theory for ladder filters is well-established, such topology imposes some restriction when acoustic wave technology is involved. As known, the transmission zeros in the upper band are implemented by series resonators, meanwhile, the shunt resonators introduce them in the lower band. This paper shows a synthesis method to obtain a new class of topologies that permits the introduction of arbitrary transmission zeros in the upper band while retaining the ladder-like shape.