In a case in which a filter circuit like the noise filter NF1 is connected, there is a method in which electronic components corresponding to the resistor AR1, the inductor AL1, and the capacitor AC1 which are shown in FIG. 2 are prepared, respectively, and the components are mounted on the wiring board 10. However, as the number of electronic components mounted on the wiring board 10 increases, restriction on a layout of components and wires becomes greater, which causes an increase of an area of the wiring board 10. Also, when discrete devices (single-function components) are gathered, respective components may interfere with one another because interference with other components is not taken into consideration, and as a result, a new noise source may be generated, in some cases.
In view of this, the present inventors have made a study of a technique of forming the noise filter NF1 using a conductor pattern formed in the wiring board 10. First, the resistor AR1 and the inductor AL1 shown in FIG. 2 can be replaced by the wire 11A shown in FIG. 1. More specifically, by adjusting a length (extending distance) and a width (a length in a direction orthogonal to an extending direction which is a longitudinal direction) of the wire 11A, it is possible to provide functions of the resistor AR1 and the inductor AL1 to the wire 11A. However, it is difficult to provide the function of the capacitor AC1 to the wire 11A because the function of the capacitor AC1 affects planar areas of electrodes which are arranged so as to face each other via a dielectric member.
