Signal separation device

A signal separation device including a first passband and a second passband that is located at higher frequencies than the first passband and that is adjacent to the first passband, the device comprising:

• a common terminal;
• a first terminal;
• a second terminal;
• a first filter unit that is electrically connected between the common terminal and the first terminal and that defines at least the first passband;
• and
• a second filter unit that is electrically connected between the common terminal and the second terminal and that defines at least the second passband;
• wherein
• the first filter unit is a ladder filter including:
• a series arm electrically connected between the common terminal and the first terminal;
• and
• a plurality of parallel arms electrically connected between the series arm and a ground potential;
• wherein
• the series arm includes at least one series arm resonator;
• the plurality of parallel arms each include at least one parallel arm resonator;
• and
• the parallel arm resonators include at least one first resonator that has a lower resonant frequency than the series arm resonator and a second resonator that has a resonant frequency which is located within the second passband and which is higher than the resonant frequency of the series arm resonator and that has a lower capacitance than the series arm resonator and the first resonator.