Yoshihiko Takeuchi

Surface Acoustic Wave Filter Composed of Interdigitated Interdigital Transducers and One-Port Resonators.

This paper describes a design method for low-loss surface acoustic wave (SAW) filters with a large stop-band attenuation. The method employs a conventional interdigitated interdigital transducer (IIDT) SAW filter and conventional one-port SAW resonators, which are constructed on one chip and connected electrically. The resonators provide a large attenuation in a specified stop band. On the other hand, the resonators act as an element in a matching circuit for the IIDT SAW filter in the passband. An 880 MHz filter was designed and fabricated according to the proposed method. The side-lobe attenuation of 45 dB in the specified stop band and the insertion loss of 2.5 dB in the passband were realized.

IIDT Type Low-Loss SAW Filters Using Withdrawal-Weighted Transducers

This paper describes a method of designing IIDT SAW filters with suppressed sidelobes and reduced insertion loss. The method employs withdrawal-weighted transducers which have almost the same frequency response in pass band and different trap-frequencies in stop bands. An 880 MHz filter was designed and fabricated according to the proposed method. The sidelobe suppression of 25 to 35 dB, the minimum insertion loss of 1.6 dB, and the 0.5 dB bandwidth of more than 20 MHz were realized.