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  A Simple Method to Accurately Predict PLL Reference Spur Levels Due to Leakage Current &mdash AN143
  PDF, 256 Kb, File published: Dec 17, 2013
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  Application Note 143
  December 2013
  A Simple Method to Accurately Predict PLL Reference
  Spur Levels Due to Leakage Current
  Michel Azarian and Will Ezell
  Presented is a simple model that can be used to accurately
  predict the level of reference spurs due to charge pump
  and/or op amp leakage current in a PLL system. Knowing
  how to predict these levels helps pick loop parameters
  wisely during the early stages of a PLL system design.
  Quick Review of PLLs
  The phase locked loop (PLL) is a negative feedback system
  that locks the phase and frequency of a higher frequency
  device (usually a voltage controlled oscillator, VCO) whose
  phase and frequency are not very stable over temperature
  and time to a more stable and lower frequency device
  (usually a temperature compensated or oven controlled
  crystal oscillator, TCXO or OCXO). As a black box, the PLL
  can be viewed as a frequency multiplier.
  A PLL is employed when there is the need for a high
  frequency local oscillator (LO) source. Example applications are numerous and include wireless communications,
  medical devices and instrumentation.
  Figure 1 shows the building blocks of a PLL system used …

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Manufacturer's Classification

• Timing > PLL Synthesizers & VCOs > Integer-N PLLs