Electrical characteristics of SAW filters on SiO2/Al/LiNbO3 structure for inverter multiplex transmission systems

To improve the power durability of interdigital transducer (IDT) electrodes, transversal type of surface acoustic wave (SAW) filters based on a SiO
₂
/Al/LiNbO
₃
structure were fabricated and their power durability, withstand voltage, and frequency temperature characteristics were measured. We have proposed a gate drive system using the SAW filters for the multilevel invertor. In our system, a transmission energy in the order of 100 mW through the SAW filters is desirable to drive switching devices. Therefore, it is important to improve the power durability of the SAW filters. The frequency temperature characteristic changed from -75.6 ppm/°C to -13.1 ppm/°C, the withstand voltage changed from 1120 V to 1351 V, and a power durability of 2.0 W was obtained by depositing a SiO
₂
film on the SAW filters with Al electrodes. These results confirmed that the SAW filter based on the SiO
₂
/Al/LiNbO
₃
structure is suitable for the proposed system.