Phase noise reduction of charge pump PLLs by using a new approach

This paper analyses phase noise properties of the second order charge-pump phased locked loops (PLLs) in order to use in MTI radars. The effect of each building block on the total output phase noise of PLL is demonstrated by mathematical relationship and graphical treatment. Phase noise transfer functions are analyzed by the superposition theory and linear operation of PLL. The output phase noise due to each source is correctly predicted by calculating the relation between an input power spectrum density and its closed-loop transfer function. There exist four noise sources which are generated by reference oscillator, voltage-controlled oscillator, filter and main divider. We will analysis these noise sources in a linear model of PLL.