Filter apparatus and radio-frequency front end circuit including the same

A filter apparatus comprising:

• a dielectric substrate including a first surface and a second surface;
• an input terminal, an output terminal, and a ground terminal on the second surface of the dielectric substrate;
• a common electrode inside of the dielectric substrate;
• and
• a first resonator, a second resonator, a third resonator, and a fourth resonator each connected to the common electrode and the ground terminal;
• wherein
• the first resonator is connected to the input terminal;
• the second resonator is connected to the output terminal;
• the third resonator and the fourth resonator are between the first resonator and the second resonator;
• each of the first resonator, the second resonator, the third resonator, and the fourth resonator includes:
• a capacitor;
• a first via including one end connected to the common electrode and another end connected to the ground terminal with the capacitor interposed therebetween;
• and
• a second via including one end connected to the common electrode and another end connected to the ground terminal without the capacitor interposed therebetween;
• in the common electrode, a direction from the first via to the second via in the first resonator is opposite to a direction from the first via to the second via in the second resonator;
• and
• a shortest path along the common electrode from the first via in the third resonator to the first via in the fourth resonator intersects with a shortest path along the common electrode from the second via in the third resonator to the second via in the fourth resonator.