SURFACE-ACOUSTIC-WAVE FILTER COMPOSED OF INTERDIGITATED INTERDIGITAL TRANSDUCERS AND ONE-PORT RESONATORS

This paper describes a design method for low-loss surface acoustic wav e (S AW) filters with a large stop-band attenuation. The method employ s a conventional interdigitated interdigital transducer (IIDT) SAW fil ter and conventional one-port SAW resonators, which are constructed on one chip and connected electrically. The resonators provide a large a ttenuation 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 th e passband. An 880 MHz filter was designed and fabricated according to the proposed method. The side-lobe attenuation of 45 dB in the specif ied stop band and the insertion loss of 2.5 dB in the passband were re alized.