title: Optimal design of an RSPUDT-based SAW filter with constant group delay.
abstract: This paper describes the application of resonant single-phase unidirectional transducers (RSPUDTs) to the development of low-loss SAW filters with constant group delay in transition bands as well as in the passband. A low-loss SAW filter with constant group delay was designed and fabricated on a 128 degrees YX-LiNbO3 substrate. Experimental results were in good agreement with the design; the group delay deviation of 20 ns was realized over the range of +/-8 MHz at the center frequency of 512 MHz. The minimum insertion loss and -3 dB bandwidth were 4.3 dB and 8.5 MHz, respectively. The application of this technique is also extended to develop high-performance wideband filters employing quasi-slanted interdigital transducers.
authors.affiliation: Institute of Acoustics, Chinese Academy of Sciences, Beijing 100080, China.
authors.forename: Honglang
authors.initials: H
authors.lastname: Li
authors.forename: Jiguo
authors.initials: J
authors.lastname: Wen
authors.forename: Ken-ya
authors.initials: KY
authors.lastname: Hashimoto
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Omori
authors.forename: Masatsune
authors.initials: M
authors.lastname: Yamaguchi