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Investigation of Mechanisms for Spur Generation in Fractional-N Frequency Synthesizers
Linköping University, Department of Electrical Engineering, Electronics System. Linköping University, The Institute of Technology.
2012 (English)Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

With the advances in wireless communication technology over last two decades, the use of fractional-N frequency synthesizers has increased widely in modern wireless communication applications due to their high frequency resolution and fast settling time.

The performance of a fractional-N frequency synthesizer is degraded due to the presence of unwanted spurious tones (spurs) in the output spectrum. The Digital Delta-Sigma Modulator can be directly responsible for the generation of spur because of its inherent nonlinearity and periodicity. Many deterministic and stochastic techniques associated with the architecture of the DDSM have been developed to remove the principal causes responsible for production of spurs. The nonlinearities in a frequency synthesizer are another source for the generation of spurs. In this thesis we have predicted that specific nonlinearities in a fractional-N frequency synthesizer produce spurs at well-defined frequencies even if the output of the DDSM is spur-free. Different spur free DDSM architectures have been investigated for the analysis of spurious tones in the output spectrum of fractional-N frequencysynthesizers.

The thesis presents simulation and experimental investigation of mechanisms for spur generation in a fractional-N frequency synthesizer. Simulations are carried out using the CppSim system simulator, MATLAB and Simulink while the experiments are performed on an Analog Devices ADF7021, a high performance narrow-band transceiver IC.

Place, publisher, year, edition, pages
2012. , 59 p.
Keyword [en]
DDSM, Digital Delta Sigma Modulator, EFM, Error Feedback Modulator, PLL Phase Locked Loop, Fractional N Frequency Synthesizer, Spur, Spurs
National Category
Other Electrical Engineering, Electronic Engineering, Information Engineering
URN: urn:nbn:se:liu:diva-80886ISRN: LiTH-ISY-EX--12/4613--SEOAI: diva2:548943
External cooperation
University College Cork/ Tyndall National Institute, Ireland
Subject / course
Electronics Systems
2012-07-03, Linkoping University, Linkoping, 10:15 (English)
Available from: 2012-09-04 Created: 2012-09-02 Last updated: 2012-09-04Bibliographically approved

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