1.5 GHz Low-Loss Surface Acoustic Wave Filter Using ZnO/Sapphire Substrate

A 1.5 GHz range low insertion loss surface acoustic wave (SAW) filter has been developed using a ZnO/sapphire substrate and IIDT-type electrodes with two external reflectors. This filter had an insertion loss of 1.3 dB, stop-band attenuation of greater than 30 dB and matching impedance of 50 Ω pure resistivity without external matching networks. This filter has the smallest insertion loss of all transverse-type GHz-range SAW filters reported previously and it is suitable for use as a RF-stage filter for future 1.5 GHz range Japanese digital cellular systems.