5 GHz Range Low-Loss Wide Band Surface Acoustic Wave Filters Using Electrode Thickness Difference Type Unidirectional Transducers

Abstract

A new electrode thickness difference type single phase unidirectional surface acoustic wave (SAW) transducer (ETD-SPUDT), which has λ/4 narrow-gap electrodes is investigated. The ETD-SPUDT is fabricated by cutting part of a meander-line electrode using the shadow of the resist pattern. The theoretical and experimental results show low-loss and large directivity. A low-loss filter for use in the 2 GHz range is fabricated on 128° Y-X LiNbO3 by optical photolithography techniques and for use in the 5 GHz range is fabricated by electron beam exposure. The results show a 3.0 dB insertion loss at 2 GHz and a 4.1 dB loss at 5 GHz.