BALANCED OPERATION TYPE SURFACE ACOUSTIC WAVE FILTER DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a balance operation type surface acoustic wave(SAW) filter device with which the terminal resistance (nominal value) of an unbalanced terminal can be easily made equal with the terminal resistance (nominal value) of a balanced terminal. SOLUTION: This SAW filter device is composed of a first SAW element 1 provided with first comb-line electrode groups 24-26 while having an unbalanced terminal 21 and a pair of balanced terminals 22 and 23 and a second SAW element 2 provided with second comb-line electrode groups 27-29. The unbalanced terminal 21 is connected to one terminal 25b of serial electrode structures 25 and 28 serially connecting one part 25a of the first comb-line electrode groups and one part 28a of the second comb- line electrode groups. One balanced terminal 22 is connected to one terminal 24a+27a of parallel electrode structures 24 and 27 parallelly connecting a first other part 24 of the first comb-line electrode groups and a first other part 27 of the second comb-line electrode groups. The other balanced terminal 23 is connected to one terminal 26a+29a of parallel electrode structures 26 and 29 parallelly connecting a second other part 26 of the first comb-line electrode groups and a second other part 29 of the second comb-line electrode groups.