Comparative Study Of Different Voltage Controlled Oscillator Using CMOS Technology

Oscillators are integral part of many electronic systems. An oscillator is an electronic device used for the purpose of generating a signal. Most electronic signal processing systems require frequency or time reference signals. This paper deals with the analysis and design of CMOS oscillators more specifically voltage controlled oscillators (VCOs).Voltage Controlled Oscillator is an electronic oscillator whose output frequency is controlled by a voltage input.VCO can be built using many circuit techniques. Primarily, there are two methods of designing CMOS VCOs, one uses a ring oscillator and other uses a Schmitt trigger. Though there are so many design requirements of a VCO, which are phase stability, large electrical tuning range, linearity of frequency verses control voltage, large gain factor, capability of accepting wideband modulation and low cost but the most important factor in designing the VCO is the linearity, on the basis of which the comparison between CMOS VCOs is described. With respect to digital phones that use these circuits, low power consumption, small size, and leakage current and low fabrication costs are important design factors. In this paper main objective is to reduce the leakage current, voltage and power consumption. It is observed by the parameters calculated.