4.5 GHz Lithium Niobate MEMS Filters With 10% Fractional Bandwidth for 5G Front Ends
This paper presents a new class of micro electro mechanical system (MEMS) C band filters for 5G front ends. The filter is comprised of resonators based on the first order asymmetric Lamb wave (A1) mode in thin film lithium niobate. Two filters have been demonstrated at 4.5 GHz with sharp roll off, flat in band group delay, and spurious free response over a wide frequency range. The first design shows a 3 dB fractional bandwidth (FBW) of 10% an insertion loss (IL) of 1.7 dB, an out of band (OoB) rejection of 13 dB, and a compact footprint of 0.36 mm2, while the second design shows a 3 dB FBW of 8.5% an IL of 2.7 dB, an OoB rejection of 25 dB, and a footprint of 0.9 mm2. The demonstrations herein mark the largest FBW achieved for acoustic only filters at 5G frequencies. [2019 0083]
Journal of Microelectromechanical Systems