Comparative Study of Cmos Fractional-N Synthesizer Based on Phase Locked Loop- A Review

Abstract

In the area of communication and wireless system PLL plays an important role for the frequency synthesizers. CMOS fractional-N synthesizer that mainly depend on PLL (phase looked loop). PLL has various application in many areas such as in frequency synthesizer, phase modulation and demodulation, frequency modulation and demodulation, data and clock recovery circuit as well as in tacking filters. The stability and the tuning range of these synthesizers mainly based on PLL. Comparison on different type of frequency synthesizers such as fractional-N synthesizer are presented and different type of parameters for the fractional-N synthesizers such as spur, power dissipation, loop bandwidth, switching speed, lock in range and phase noise are defined for the fractional-N synthesizer.