Acoustic wave filter device utilizing filters having different acoustic wave propagation directions

An acoustic wave filter device comprising:

• a piezoelectric substrate;
• a first longitudinally coupled resonator type acoustic wave filter which is disposed on the piezoelectric substrate and has a plurality of IDT electrodes and first and second terminals;
• and
• a second longitudinally coupled resonator type acoustic wave filter which is disposed on the piezoelectric substrate and has a plurality of IDT electrodes and third and fourth terminals;
• wherein
• the acoustic wave filter device has a balanced-to-unbalanced conversion function in which, when identical signals are input to the first terminal and the third terminal, a phase difference between a signal output from the second terminal and a signal output from the fourth terminal is approximately 180 degrees in at least a pass band;
• the first and third terminals are commonly connected and connected to an unbalanced terminal;
• and
• the second and fourth terminals are set as first and second balanced terminals, respectively;
• a propagation direction of an acoustic wave in the first longitudinally coupled resonator type acoustic wave filter and a propagation direction of an acoustic wave in the second longitudinally coupled resonator type acoustic wave filter are different from each other.