BAND-PASS FILTER HAVING ASYMMETRIC FILTER RESPONSE

摘要

PROBLEM TO BE SOLVED: To provide a band-pass filter and its manufacturing method in which adverse effects due to temperature variation is reduced.;SOLUTION: An array of acoustic resonators, in which asymmetric filter responses are realized in target frequency bands, is included in the band-pass filter. The acoustic resonators are preferably thin-film bulk acoustic resonators. The filter is constituted, so that it has an insertion loss profile 56 in which a minimum insertion loss point of the filter is located at a first frequency end (1,910 MHz) of a pass-band or the vicinity of the end and a maximum insertion loss point of the filter is located at the reverse frequency end (1,850 MHz) of the pass-band or the vicinity of the end. Moreover, when the filter is used for transmission, the zero and the pole of the thin film bulk acoustic resonator array are selectively arranged and is constituted, so that the minimum insertion loss point is located at the high-frequency end of the filter response or the vicinity of the end.;COPYRIGHT: (C)2002,JPO