Acoustic wave device, radio frequency module, and communication device

An acoustic wave device, comprising:

• a first transmission filter;
• and
• a second transmission filter stacked on the first transmission filter so that a first functional surface of the first transmission filter and a second functional surface of the second transmission filter face each other at a predetermined distance, wherein
• the first transmission filter includes a first input terminal, a first output terminal and a first acoustic wave resonator,
• the first acoustic wave resonator includes a first functional electrode on the first functional surface,
• the second transmission filter includes a second input terminal, a second output terminal and a second acoustic wave resonator,
• the second acoustic wave resonator includes a second functional electrode on the second functional surface,
• the first transmission filter further includes a third acoustic wave resonator which is on the first functional surface and is closer to the first output terminal than the first acoustic wave resonator is to the first output terminal,
• the second transmission filter further includes a fourth acoustic wave resonator which is on the second functional surface and is closer to the second output terminal than the second acoustic wave resonator is to the second output terminal, and
• in a plan view along a thickness direction of the first and second transmission filters:
• a first formation region of the first functional electrode and a second formation region of the second functional electrode do not overlap each other, and
• the third acoustic wave resonator and the fourth acoustic wave resonator overlap each other.

A radio frequency module, comprising:

• a mounting substrate;
• a first transmission filter disposed on the mounting substrate;
• a second transmission filter disposed above the first transmission filter;
• and
• a conductive connection member connected to the mounting substrate and separating the second transmission filter from the substate, wherein
• the first transmission filter includes a first input terminal connected to a first power amplifier, and a first plurality of acoustic wave resonators,
• the first plurality of acoustic wave resonators includes a first acoustic wave resonator,
• the second transmission filter includes a second input terminal connected to a second power amplifier, an output terminal and a second plurality of acoustic wave resonators,
• the second plurality of acoustic wave resonators includes a second acoustic wave resonator and a third acoustic wave resonator,
• the first acoustic wave resonator further includes a first functional electrode on a first functional surface of the first transmission filter,
• the second acoustic wave resonator further includes a second functional electrode on a second functional surface of the second transmission filter,
• the second transmission filter is disposed to face the first transmission filter in a thickness direction of the second transmission filter,
• the third acoustic wave resonator is closer to the output terminal than the second acoustic wave resonator is to the output terminal, and
• in a plan view along a thickness direction of the first and second transmission filters:
• a first formation region of the first functional electrode and a second formation region of the second functional electrode do not overlap each other, and
• the first acoustic wave resonator and the third acoustic wave resonator overlap each other.