5-GHz Wideband Acoustic Filter with FBW of 20% Based on Z-Cut Lithium Niobate

This work presents A1-mode Lamb wave resonators based on Z-cut lithium niobate thin film to realize acoustic filters at 5 GHz. By using half-electrode reflectors and fin-type anchors, a high-performance resonator with excellent Figure of Merit (FoM) up to 316 has been implemented. The fabricated ladder-type filter achieves a 3-dB bandwidth (3dB-BW) of 990 MHz, equivalent to a fractional bandwidth (FBW) of 20% and an insertion loss (IL) of 1.85 dB at 4990 MHz. This demonstration proves great potential of Lamb wave acoustic filters based on lithium niobate for future 6G and Wi-Fi 7 applications.