An RF filter assembly comprising a monoblock of dielectric material defining a first RF filter and a lid of dielectric material defining a second RF filter. The apparatus of the invention includes a lamp unit, a current restricting unit coupled to the lamp unit, and a current sensing unit that is coupled to the current restricting unit. The V-shaped bottom wall also centers and balances the rolls during the rolling process resulting in a more accurate cross-section of the fastener. Moreover, a switch that consists of the NMOS transistor is connected between a node, which is between one capacitor and one switch, and a node, which is between the other capacitor and the other switch, and the two nodes are connected to each other when the switch is closed. Other embodiments are also described and claimed. The reference voltage signal lines on the mutually different layers are respectively connected to impurity diffusion layers of the transistors that are adjacent in the row direction.