Over-1 GHz Bandwidth Filter Based on Y-128° Cut Lithium Niobate on Amorphous Silicon

This paper reports on the demonstration of a 6.2 GHz acoustic filter with an over-1 GHz bandwidth, a 30 dB out-of-band rejection, and a sharp roll-off. The demonstrated filter employs the first-order antisymmetric (A1) lamb wave in Y-128° cut lithium niobate thin film to maximize the electromechanical coupling $\left( {k_{\text{t}}^2 = 48\% } \right)$. Amorphous Si is utilized to decrease the parasitic conductor effect and feedthrough for better out-of-band rejection of the filter. The ultrawide passband proves the promising potential of lithium niobate thin films in WIFI 7 and 6G applications.