title: New electrode separation technology using anodic oxidation and application to SAW interdigital transducers.
abstract: By anodic oxidation of the edges of the portions of the Al film under photoresist, controllable gaps between electrodes with good insulation can be obtained. These techniques are applied to realize a surface-acoustic-wave (SAW) narrow gap interdigital transducer (NG-IDT) and narrow gap unidirectional transducer (NG-UDT). The experimental result shows 7.2 dB insertion loss with amplitude ripples of +/-1.2 dB for a conventional NG-IDT. Directives of 3-dB/transducer at 440 MHz (fundamental) and 13-dB transducer at 870 MHz (second-harmonic operation) for a new floating electrode type unidirectional transducer (NG-FEUDT) are demonstrated. Also a three transducer low loss filter using a combination of NG-IDT and NG-FEUDT exhibits 3.46 dB insertion loss at 894 MHz (second-harmonic operation, electrode width of 1.7 mum) with sidelobe suppression greater than 35 dB.
authors.affiliation: Res. Inst. of Electr. Commun., Tohoku Univ., Sendai.
authors.forename: K
authors.initials: K
authors.lastname: Yamanouchi
authors.forename: T
authors.initials: T
authors.lastname: Meguro
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto