Analytical model and behavioral simulation approach for a ΣΔ fractional-N synthesizer employing a sample-hold element

Marco Cassia, Peter Jivan Shah, Erik Bruun

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A previously unknown intrinsic nonlinearity of standard SigmaDelta fractional-N synthesizers is identified. A general analytical model for SigmaDelta fractional-N phased-locked loops (PLLs) that includes the effect of the nonlinearity is derived and an improvement to the synthesizer topology is discussed. Also, a new methodology for behavioral simulation is presented: the proposed methodology is based on an object-oriented event-driven approach and offers the possibility to perform very fast and accurate simulations, and the theoretical models developed validate the simulation results. We show a GSM example to demonstrate the applicability of the simulation methodology to real study cases.
Original languageEnglish
JournalIEEE transactions on circuits and systems - 2, Analog and digital signal processing
Issue number11
Pages (from-to)850-859
Publication statusPublished - 2003

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  • nonlinearities
  • phase noise
  • phase-locked loops
  • simulation
  • sigma-delta modulation
  • Linear systems

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