Synthesis and Design of a Wideband Acoustic Wave Bridge-T Filter

This paper introduces a Bridge-T (BT) topology that integrates acoustic wave resonators with planar technology to create an excepcionally wideband filter, achieving a fractional bandwidth (FBW) of 33.81%. The resonators employ solidly-mounted Bulk Acoustic Wave (BAW) technology and they are implemented on a 550μm x 750μm die-size. The rest of the circuit is built on a 7-layer laminate with a total size of 3mm x 2mm. This combination allows for very wide fractional bandwidth by utilizing resonators with low electromechanical coupling coefficient, contributing to the minimization of insertion loss in the overall response. The proposed BT topology is synthesized through a series of coupling matrix similarity transformations, enabling the extraction of all lumped elements directly in the bandpass domain. The synthesis procedure is validated through the electromagnetic simulation of the designed filter.