VCO Performance Simulations

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The following tutorial assumes that you have a voltage controlled oscillator (VCO) already designed and you now wish to find various performance criteria such as phase noise, tuning range, etc.

Phase Noise

  • Make sure that your tuning voltage is set such that your VCO oscillates at the desired frequency.
  • From the Analog Design Environment click "Choose Analysis ..." and choose "pss"
    • In the "Fundamental Tones" section make sure "Beat Frequency" is selected and enter your best guess as to what the frequency of oscillation should be (i.e., enter your desired operating frequency). Make sure that "Auto Calculate" is NOT selected.
    • In "Output harmonics" select "Number of harmonics" and enter 10.
    • Under "Accuracy Defaults (errpreset)" select "conservative" and enter the required stabilization time under "Additional Time for Stabilization (tstab)" that you obtained from a transient simulation.
      • tstab is obtained from a transient simulation. It is the time that it takes for the output of your oscillator to settle to a steady state (in terms of amplitude and frequency).
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