Fabrication of 2.5 GHz SAW retiming filter with SiO2/ZnO/diamond structure

The variety of layered structures with a diamond film are expected to be applied for high-frequency SAW devices due to their high velocities. SiO2/ZnO/IDT/diamond structure is one promising, especially for high-frequency and narrowband filters. In this paper, the Ist mode SAW in the SiO2/ZnO/IDT/diamond structure was experimentally studied, and confirmed that it can provide zero temperature coefficient of frequency (TCF) as well as high velocity of 9,000 m/s. A 2.5 GHz narrow-band SAW filter was successfully fabricated with this structure with IDTs of 0.9 mu m finger width, and it was shown that this filter has practical and superior characteristics for the 2.5 GHz retiming filter. Its insertion loss was 10 dB that is smaller than ever reported with quartz.