title: Correspondence - Design of ladder-type SAW/BAW.
abstract: This paper describes the design of RF SAW/ BAW filters with constant group delay. The band-pass LC filter is designed based on the traditional Bessel filter design. Then, LC resonators in the filter are replaced by SAW/BAW resonators with finite capacitance ratio γ. Finite γ generates passband ripples in the group delay. However, it is shown the ripples can be suppressed by optimal design of the SAW/BAW resonators. Norton's first transform is also applied to the designed filter to reduce variation of resonator shunt capacitances. Finally, extremely flat group delay with deviation of 4 ns over the frequency range of ±20 MHz at the center frequency of 1 GHz is theoretically demonstrated.
authors.forename: Hualei
authors.initials: H
authors.lastname: Wang
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Yu
authors.initials: Y
authors.lastname: Shi
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Omori
authors.forename: Changjun
authors.initials: C
authors.lastname: Ahn
authors.forename: Ken-ya
authors.initials: KY
authors.lastname: Hashimoto