Ridge-shaped periodically poled transducer for wide band R-F filter

Transducer on Periodically Poled Lithium Niobate (PPLN) exhibiting an electromechanical coupling about 20% and an equivalent phase velocity about 10 km.s^-1 were shown in [1]. These transducers are 3D structured to overcome Surface Acoustic Wave (SAW) and Bulk Acoustic Wave (BAW) technological limits, such as short circuit between electrodes for SAW and precise thickness control for BAW. The present work shows the use of these 3D structured transducers for Radio Frequency (RF) filtering. An acoustic filter showing a band pass of about 5MHz has been realized on Lithium Niobate at 250MHz. This filter is made of PPLN exhibiting a poling period of 14.9μm.