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Nonlinear behavioural model of charge pump PLLs
Author(s) -
Brambilla Angelo,
Linaro Daniele,
Storace Marco
Publication year - 2013
Publication title -
international journal of circuit theory and applications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.364
H-Index - 52
eISSN - 1097-007X
pISSN - 0098-9886
DOI - 10.1002/cta.1813
Subject(s) - phase locked loop , nonlinear system , context (archaeology) , electronic engineering , charge pump , noise (video) , phase noise , block (permutation group theory) , computer science , control theory (sociology) , voltage , phase (matter) , engineering , electrical engineering , physics , mathematics , capacitor , paleontology , geometry , control (management) , quantum mechanics , artificial intelligence , image (mathematics) , biology
SUMMARY Despite the nonlinear nature of even the simplest versions of phase locked loops (PLLs), linear models are still used during the first phases of the design of modern PLLs. Even though the linear model may represent a crude approach, its use is justified by the fact that accurate numerical simulations often require a too large amount of CPU time, being PLLs by construction stiff circuits, characterised by very different time scales. This aspect has triggered the need for compact models that allow fast and accurate numerical simulations. The scientific literature numbers several models that have been developed with different approaches and tailored to different simulation environments. In this context, we propose a nonlinear model of a type‐II PLL, which (1) considers both the switching behaviour of the phase/frequency detector and charge pump and the complex dynamics (including the presence of amplitude and phase noise) of the voltage controlled oscillator, (2) is compact and can be easily implemented in modern mixed analog/digital simulators as a behavioural block, and (3) allows the simulation of spurs owing to the nonlinearities of both the charge pump and the fractional frequency divider. Copyright © 2012 John Wiley & Sons, Ltd.