PLL Phase Margin

Calculate loop phase margin from unwrapped open-loop phase at the unity-gain crossover frequency.

Description

Calculate loop phase margin from unwrapped open-loop phase at the unity-gain crossover frequency.

PLL Phase Margin: Calculate loop phase margin from unwrapped open-loop phase at the unity-gain crossover frequency.

When to use PLL Phase Margin

Use this electronics calculation for a first-pass component, converter, signal, motor, or sensor estimate when the stated operating conditions and units match the device data.

Loop phase at 0 dB (°)
Required number input.

How PLL Phase Margin works

Calculate loop phase margin from unwrapped open-loop phase at the unity-gain crossover frequency. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.1

Phase margin (°)
The resulting phase margin returned as a number.

Limitations and assumptions

  • PLL bandwidth, margin, lock time, output frequency, spur, and integrated-jitter estimates depend on loop order, charge pump, divider values, oscillator gain, reference noise, nonlinear acquisition, and the exact phase-noise integration limits. Simplified linear models primarily describe locked small-signal behavior.
  • Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Alternative or Complementary approaches

Check the result against the current datasheet and worst-case operating corners, then verify the circuit or measurement with simulation and bench testing where failure matters.

References

  1. Phase-locked loop — Wikipedia contributors

Similar or alternative tools

  • PLL Gain Margin

    Calculate loop gain margin from open-loop gain in decibels at the minus-180-degree phase crossover.

  • Finite-Gain Closed-Loop Error

    Calculate feedback closed-loop gain A/(1+Aβ) and percent error relative to ideal 1/β. Assumes negative feedback with positive real open-loop gain and feedback factor; frequency dependence is excluded.

  • Op-Amp Open-Loop Gain

    Calculate open-loop voltage gain A=Vout/(V+−V−) from an unsaturated operating-point measurement. Differential input cannot be zero; this scalar does not capture frequency-dependent gain.

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