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Hier finden Sie wissenschaftliche Publikationen aus den FraunhoferInstituten. Exact and approximated discretetime nonlinear models of voltage switched CPPLL
 Institute of Electrical and Electronics Engineers IEEE: IEEE 58th International Midwest Symposium on Circuits and Systems, MWSCAS 2015. Conference Proceedings : "Climbing to New Heights", August 25, 2015, Fort Collins, Colorado, USA Piscataway, NJ: IEEE, 2015 ISBN: 9781467365574 4 pp. 
 International Midwest Symposium on Circuits and Systems (MWSCAS) <58, 2015, Fort Collins/Colo.> 

 English 
 Conference Paper 
 Fraunhofer ENAS () 
Abstract
The chargepump phase locked loop (CPPLL) is a mixed signal system and it is a challenging task for a designer to analyze the exact switching behavior of the PLL using any general concept of feedback systems. As the order of the loop filter (LF) is enhanced to cancel prefilter noise and spurious signals, the more complexity in analysis is inevitable. The PLL operating with a voltage switched chargepump (VSCP) is a complicated system, since the system representation is not unique in all switching states of the phase and frequency detector (PFD). Therefore, it is not possible to characterize the system with a unique transfer function. In this paper, an exact discretetime nonlinear model of the VSCPPLL is presented using efficient Event Driven (ED) modeling. By assuming a constant voltage at control node in the zerostate, the approximation model is demonstrated, which can be sufficient to use without complicating the analysis up to some extent. The EDsimulation of the exact model is validated using an equivalent transistor level model designed in 130nm CMOS process. The ability of both exact and approximation model is mapped applying a ramping reference frequency.