FILTER CIRCUIT, DIPLEXER, RADIO-FREQUENCY FRONT-END CIRCUIT, AND COMMUNICATION DEVICE

原文（中国語）

A filter circuit is located in a dielectric substrate and includes multiple dielectric layers and a pass band in a range higher than a predetermined frequency. The dielectric substrate includes first and second major surfaces facing each other. External terminals for connection with an external device are on the second major surface. The filter device includes a first terminal, a second terminal, and first and second resonant circuits. The first resonant circuit is connected between the first and second terminals. The second resonant circuit is connected between the first resonant circuit and a ground potential. Each of the first and second resonant circuits includes an LC resonant circuit including a capacitor and an inductor. In the dielectric substrate, a portion of an inductor in the second resonant circuit is on or in a dielectric layer between the first major surface and inductors included in the first resonant circuit.