The present invention provides a filter. The filter includes two common electrode layers and two inner electrode layers, where the two inner electrode layers are located between the two common electrode layers, and an electrical insulation layer is disposed between any two adjacent electrode layers of the two common electrode layers and the two inner electrode layers; each of the two common electrode layers is connected to at least one grounding electrode; and each of the two inner electrode layers is connected to at least one signal electrode. The filter provided by embodiments of the present invention can perform filtering processing on low-frequency noise such as that of a direct current power supply, and has a good filtering processing effect.