A voltage controlled oscillator (VCO) is a standout amongst the most imperative fundamental building obstructs in simple and advanced circuits. Like some other circuit, with a VCO there are various outline necessities that should be known from the earliest starting point of the plan procedure. These essential prerequisites for the VCO will represent a considerable lot of the choices concerning the circuit topology and other crucial parts of the circuit. A portion of the fundamental prerequisites are Tuning range, Tuning pick up, tuning shift for a given tuning voltage change and low stage noise. This paper discuss about voltage control oscillator.