fmusa_pllnoiseNoise Analysis of Phase Locked Loops and System Trade-offs Faisal A. Musa ABSTRACT This report analyzes phase locked loops from the noise point of view and discusses the different trade-offs in designing low noise PLLs. Beginning with a rst order loop, the importance of loopbandwidth is explained. It is shown that the loopbandwidth basically acts as a threshold when the VCO noise begins to dominate over the input noise. Higher order loops are also analyzed to show that two basic PLL parameters: the charge pump gain and the resistance in the loop lter can be varied for reducing the noise level at the output. However, variation of these parameters disturb stability and frequency spectrum of the PLL. Trade-offs in varying these parameters are discussed and a step by step PLL design procedure ……