A jitter generation apparatus for applying a phase modulation to a PLL is controlled by a control unit so as to output a signal with the desired jitter based on a parameters. The zoom lens includes: a first lens group having a negative refractive power; a second lens group having a positive refractive power; and a third lens group having a positive refractive power, which are sequentially arranged in a direction from an object side to an image side, wherein the first lens group comprises a first lens that is biconcave and is closest to the object side. A metal filler may be formed within the at least one anchor via, the metal filler having a protruding portion extending from a backside of the semiconductor substrate.