6.2 GHz Lithium Niobate MEMS Filter with FBW of 11.8% and IL of 1.7 dB

This work presents a wideband radio-frequency micro-electro-mechanical system (MEMS) filter at 6.2 GHz that enables acoustic filters towards high frequencies beyond 6 GHz. The filter is comprised of resonators operating in the first-order antisymmetric (A1) Lamb wave mode and fabricated on Z-cut lithium niobate (LN) with 320-nm-thick suspended continuous thin film. Due to the spurious-free and high electromechanical coupling (k²) performance of the A1-mode LN resonators, the implemented MEMS filter demonstrates small in-band ripple and wide bandwidth (BW). Specifically, the measured result of the filter exhibits center frequency at 6.2 GHz, 3-dB fractional bandwidth (FBW) of 11.8% (BW = 734 MHz), insertion loss (IL) of 1.7 dB, and out of band (OoB) rejection of 25 dB.