A 19 GHz Lithium Niobate Acoustic Filter with FBW of 2.4%

This paper presents the first demonstration of a wideband hy-brid monolithic acoustic filter in the K-band which exceeds the limitation of electromechanical coupling on the fractional band-width (FBW) of acoustic filters. The hybrid filter utilizes the co-design of EM and acoustic to attain wide bandwidth while keep-ing the advantages of small sizes and high Q in the acoustic do-main. The fabricated filter built with resonators having an elec-tromechanical coupling of 0.7% based on the seventh-order anti-symmetric Lamb wave mode (A7) has a 3 dB FBW of 2.4% at 19 GHz, and a compact footprint of 1.4 mm2.