Design and performance of wide-band IIDT-type SAW filters with low loss and improved sidelobe suppression

Wideband low-loss surface-acoustic-wave (SAW) filters employing interdigitated interdigital transducers (IIDTs) suitable for cellular radio systems are presented. The filters were fabricated on 36 degrees Y-X LiTaO/sub 3/ substrates. The sidelobe suppression has been improved by withdrawal weighting techniques. A design method which optimizes the weighting functions and the number of fingers has been worked out. In the 500-MHz band, fractional bandwidths of up to 5.2% with passband ripples smaller than 1 dB were attained. Insertion loss and sidelobe suppression were at 1.8 dB and 23 dB, respectively.<<ETX>>

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