Voltage controlled oscillator characterize unique materials for investigation the phenomena at the nanoscale. Different types of oscillator are described in the main text and for that voltage controlled oscillator leakage reduction is also necessary for perfect performance of circuit. So different power reduction techniques are applied on the main circuit. In this book first section describes the basic introduction of oscillator and second section explain the sub circuits and application of voltage controlled oscillator and third and fourth section describe the power reduction technique applied on the voltage controlled oscillator and comparative study is provided with excellent performance of VCO