Timing jitter is one of the most significant phase-locked loop characteristics, with high impact on performance in a range of applications. It is, therefore, important to develop the tools necessary to study and predict PLL jitter performance at design time. In this paper a discrete-time, linear, cyclostationary PLL model for jitter analysis is proposed, which accounts for the cyclostationary nature of noise injected into the loop at various PLL components. The model also predicts the aliasing of jitter due to the downsampling and upsampling of frequencies around the PLL loop. Closed-form expressions are derived for the output jitter spectrum and match well with results of event-driven simulations of a 3rd-order PLL.
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