Wideband Spurious-Free Lithium Niobate RF-MEMS Filters

This paper reports on the demonstration of wideband spurious-free radio frequency micromechanical systems filters based on one-port shear horizontal (SH0) mode lithium niobate (LiNbO3) laterally vibrating resonators (LVRs). The fabricated filter has been demonstrated with an unprecedented spectral range of spurious-free response (290% of the center frequency), a low insertion loss of 2.1 dB, an excellent 30-dB shape factor of 1.48, and a 3-dB fractional bandwidth of 8.9%. The spurious free response is achieved by optimizing the building blocks of the filters, namely the LVRs, and employing a spurious mitigation design based on arraying single resonators with only two electrodes. The low loss and excellent shape factor are enabled by the demonstrated high electromechanical coupling (kt2= 16.1%), high quality factor (Q = 1093), and high figure of merit (FoM = 154) of the fabricated resonator arrays.