Exploring Surface Acoustic Wave Transversal Filters on Heterogeneous Substrates for 5G N77 Band

This work explores the design of large bandwidth acoustic filters for the 5G N77 band by combining transversal topology with surface acoustic wave (SAW) resonators based on heterogeneous substrates. Compared with traditional topologies, the transversal topology can break the limit of the fractional bandwidth (FBW) of the filter by the electromechanical coupling coefficient $(\boldsymbol{K}^{2})$ of the resonator. In contrast to bulk acoustic wave (BAW) resonators, SAW resonators features the lithography-defined frequencies, which can meet the multi-frequency design requirements in transversal topology. This work investigates the potential problems in the design of the SAW transversal filters on heterogeneous substrates and builds a SAW transversal filter covering the 5G N77 band through simulation. This work shows the feasibility of transversal SAW filters and provides research ideas for implementing large bandwidth SAW filter design.