Unidirectional SAW transducer for GHz frequencies

A SPUDT structure employing /spl lambda//4 and wider electrodes is introduced. The design and its variants exploit the significant difference between the reflectivity of short-circuited /spl lambda//4 electrodes and that of floating wide electrodes on 128/spl deg/ LiNbO/sub 3/. The SAW devices operating at 2.45 GHz have critical dimensions of about 0.4 /spl mu/m, accessible for standard optical lithography. When matched, the fabricated SPUDT filters exhibit minimum insertion losses of 5.5-7.9 dB together with 3 dB pass-bands of 95-102 MHz.