Temperature-driven Degradations on Lithium Niobate MEMS Acoustic Filter

This paper reports an experimental study on the performance of a lithium niobate MEMS filter under extreme temperatures. The filter is measured from -100°C to 180°C, and performance degradation is analyzed to identify the extra deformation-driven mechanical loss. The low-temperature degradation is driven by mechanical loss with thin film deformation, which occurs with thermal stress from the coefficient of thermal expansion mismatch. High-temperature degradation is mainly due to electrical loss. At high temperatures, the first-order antisymmetric Lamb wave (A1) mode filter exhibits a TCF of -50 ppm/K at the temperature range from 20°C to 180°C, with minimum insertion loss linearly increasing from 2 dB to 2.4 dB.