The present invention relates to a device which comprises a light source of a light emitting device, and more particularly to a circuit board, a backlight unit and a liquid crystal display device with the same. The memory element includes a first electrode, a resistivity interfacial layer having a first surface coupled to said first electrode; a resistance changing material, e. The main duct is delimited by at least one first series of elongate first welded strips, the first intermediate spaces which are in line with one another. At least one hybrid coupler circuit has input ports coupled with outputs of the main amplifier circuit and auxiliary amplifier circuit. When a current flows through the stack, electrons are reflected by the surface of the soft magnetic interlayer and thus a path for the electrons is narrowed.