An 880 MHz ladder filter formed by arrays of laterally vibrating thin film Lithium Niobate resonators

This paper reports on the first implementation of a ladder filter using Lithium Niobate based laterally vibrating resonator arrays. This demonstration is made possible by optimizing the device design parameters and using a distributed configuration of resonator arrays to simultaneously reduce spurious vibrations and insertion loss in a low impedance RF system. The designed distributed ladder filter, with a chip footprint of 0.5 mm², consists of 37 resonators that are divided into 3 series and 2 shunt resonator arrays. The fabricated ladder filter based on LN LVRs showed an insertion loss of 3.5 dB and fractional bandwidth of 2.2%.