LADDER TYPE ELASTIC WAVE FILTER AND ANTENNA DUPLEXER USING THE SAME

摘要

PROBLEM TO BE SOLVED: To suppress Q value deterioration of a ladder type elastic wave filter.;SOLUTION: The ladder type elastic wave filter is a ladder type elastic wave filter in which a serial resonator and a parallel resonator are connected in the shape of a ladder, and includes: a first parallel resonator which is connected between a signal route and ground and forms an attenuation pole in a frequency being double passband or more and a triple passband or less of the ladder type elastic wave filter and an inductor connected serially to the first parallel resonator; and a second parallel resonator 19 connected between the signal route and the ground and having a capacity smaller than that of the first parallel resonator, wherein the second parallel resonator 19 is provided with a plurality of input and output IDT electrode pairs 25, 26 and 27 which are acoustically coupled, and the plurality of input and output IDT electrode pairs 25, 26 and 27 are connected in series.;COPYRIGHT: (C)2011,JPO&INPIT