1.9 GHz Low-Loss Surface Acoustic Wave Filter: Lift-Off Method and 3 mm Square Small Size Package

Abstract

A novel 1.9 GHz low-loss surface acoustic wave (SAW) filter for personal handy phone systems has been produced. The 0.5 µm line and space electrode of SAW filter on the LiTaO3 substrate was fabricated by the lift-off process using negative photoresist. A deep UV light source was used in the photo exposure process. Electrodes with 0.2 µ m gap could be easily formed by the lift-off process. This SAW filter chip was mounted in the new small size (3.0 mm square) leadless ceramic package. Because the parasitic inductance and capacitance of this package are smaller than the usual 4.8 mm×5.2 mm package, a 1.9 GHz filter with small insertion loss of 1.7 dB was obtained. The suppression level of this filter at 4.5 GHz was greater than 30 dB.