Single Crystal LiNbO₃ and LiTaO₃ Bulk Acoustic Wave Resonator

Abstract

Since the last decade, new innovative acoustic devices based on single crystal LiNbO3 and LiTaO 3 thin films, i.e. layered surface, Lamb or bulk acoustic wave (SAW, Lamb, BAW) devices, have emerged as appealing candidates for the next generation of RF devices. In this work, we have designed and fabricated a 200 mm LiNbO3 solidly-mounted filter which exhibits performances compatible with specifications for n79 band, i.e. a central frequency of 4.6 GHz, a fractional bandwidth of 680 MHz and minimum insertion loss of 1.1 dB, largely limited by resistive losses in the thin electrodes. While the filter rejection remains modest (9 dB), due to the low order of the filter and spurious contributions due to the design of the Bragg mirror, these results demonstrate a first step towards the development of LiNbO3 BAW filters for next generation of RF filters.