Unidirectional SAW transducer for GHz frequencies
A SPUDT structure employing λ/4 and wider electrodes is introduced. The design and its variants exploit the significant difference between the reflectivity of short-circuited λ/4 electrodes and that of floating wide electrodes on 128° LiNbO3. The SAW devices operating at 2.45 GHz have critical dimensions of about 0.4 μm, 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.