5 GHZ RANGE LOW-LOSS WIDE-BAND SURFACE-ACOUSTIC-WAVE FILTERS USING ELECTRODE THICKNESS DIFFERENCE TYPE UNIDIRECTIONAL TRANSDUCERS

A new electrode thickness difference type single phase unidirectional surface acoustic wave (SAW) transducer (ETD-SPUDT), which has lambda/4 narrow-gap electrodes is investigated, The ETD-SPUDT is fabricated bq cutting part of a meander-line electrode using the shadow of the resi st pattern, The theoretical and experimental results show low-loss and large directivity. A low-loss filter or use in the 2 GHz range is fab ricated on 128 degrees Y-X LiNbO3 by optical photolithography techniqu es and for use in the 5 GHz range is fabricated by electron beam expos ure. The results show a 3.0 dB insertion loss at 2 GHz and a 4.1 dB lo ss at 5 GHz.