Resonance-frequency modulation for a robust RF SAW filter design against temperature variations

Abstract

We experimentally investigate the temperature-variant effects of surface acoustic wave (SAW) resonators and filters that are designed and fabricated on LiTaO3 piezoelectric substrate. Varying the temperature from - 30 to 85celcius (i.e., - 30, 25, 55, 85celcius), S-parameters for test SAW devices are measured in the frequency range of 50 MHz-6 GHz using a vector network analyzer (VNA). It is shown that temperature has a substantial effect on the physical characteristics of SAW-based RF filters. Then, we propose a new resonator modulation technique that can design robust RF filters against temperature-variations. We verify that the SAW resonator modulation technique can efficiently compensate for the temperature-variant effects by substantially improving the skirt characteristics of SAW-based RF filters.