A three-piece lens assembly comprises: a first lens group, a second lens group, a third lens group and an aperture. For example, disclosed RF amplifier circuits may employ a baseband decoupling network connected in parallel with a low-pass RF matching network of the amplifier circuit. The virtual smart card driver communicates with an authentication client to authenticate a user, and access the user’s private key stored in the secure key store when the user’s physical smart card is unavailable. The cam essentially is in the shape of a cylinder, and includes a cam surface and defines a cam hole extending therethrough. A tactile feedback device provides feedback as the capacitive switch is being actuated. Because the influence of the characteristic difference of an underlying layer on the formation of the USG film 5 can be avoided due to the existence of the oxide film, the USG film 5 can be formed in a uniform thickness over regions including the semiconductor substrate 1, the P-type active region 3 and the N-type active region 2.