An Analytical Approximation for the Pull-Out Frequency of a PLL Employing a Sinusoidal Phase Detector

  • Huque, Abu-Sayeed (Department of Electrical Engineering, University of Tabuk) ;
  • Stensby, John (Department of Electrical and Computer Engineering, University of Alabama Huntsville)
  • Received : 2012.03.11
  • Accepted : 2012.10.04
  • Published : 2013.04.01


The pull-out frequency of a second-order phase lock loop (PLL) is an important parameter that quantifies the loop's ability to stay frequency locked under abrupt changes in the reference input frequency. In most cases, this must be determined numerically or approximated using asymptotic techniques, both of which require special knowledge, skills, and tools. An approximating formula is derived analytically for computing the pull-out frequency for a second-order Type II PLL that employs a sinusoidal characteristic phase detector. The pull-out frequency of such PLLs can be easily approximated to satisfactory accuracy with this formula using a modern scientific calculator.


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