Composite filter device

A composite filter device comprising:

• a first filter and a second filter each including at least one series-arm resonator and at least one parallel-arm resonator;
• a first piezoelectric substrate including a first main surface and a second main surface on opposite sides;
• a first acoustic wave resonator including a functional electrode on the first main surface of the first piezoelectric substrate, the first acoustic wave resonator being included in the first filter;
• a wiring electrode on the first main surface of the first piezoelectric substrate, the wiring electrode not being connected to a signal potential;
• a support on the first main surface of the first piezoelectric substrate and surrounding the first acoustic wave resonator;
• a second piezoelectric substrate on the support and including a third main surface and a fourth main surface on opposite sides, the third main surface being closer to the support than the fourth main surface;
• and
• a second acoustic wave resonator including a functional electrode on the third main surface of the second piezoelectric substrate, the second acoustic wave resonator being included in the second filter;
• wherein
• the first acoustic wave resonator and the second acoustic wave resonator are located in a space defined by the first main surface of the first piezoelectric substrate, the third main surface of the second piezoelectric substrate, and the support;
• the second acoustic wave resonator is a parallel-arm resonator higher in resonant frequency than any other parallel-arm resonator of the second filter or a series-arm resonator lower in resonant frequency than any other series-arm resonator of the second filter;
• and
• the second acoustic wave resonator and the wiring electrode overlap each other when viewed in plan.