Fabrication of 2.5 GHz SAW retiming filter with SiO/sub 2//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. The SiO/sub 2//ZnO/IDT/diamond structure is one of the promising, especially for high-frequency and narrow-band filters. In this paper, the 1st mode SAW in the SiO/sub 2//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 /spl 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.