Jitter and Wander

You may hear the terms Jitter and Wander when thinking about Clock systems. What is the difference between Jitter and Wander? The fluctuations caused by other frequencies superimposed on the Clock are called Jitter and Wander. The difference between Jitter and Wander is the difference in superimposed frequencies.
In general, I think the following definitions are fine.

Jitter: superimposed frequency above 10Hz
Wander: superimposed frequencies below 10Hz

Analog PLL can suppress Jitter, but it is not suitable for suppressing Wonder. This is because the time constant increases and the attenuation in the filter increases. Also, even if an amplifier is used, the S/N in the low frequency band is a concern. With Digital PLL, even a 0.1Hz Cut Off can suppress attenuation in the Filter, so Digital PLL is usually used to remove wander. Why should we care so much about suppressing Jitter and Wander? The magnitude of Jitter and Wander fluctuations is indicated by Unit Interval.

For example, if 0.5UI Jitter or Wander is superimposed, data cannot be received correctly, that is, a bit error occurs. Therefore, unless Jitter and Wander are suppressed, communication quality cannot be maintained. Each communication standard stipulates Jitter Tolerance, Output Jitter regulation, Output signal Eye opening, Wander tolerance, tolerance to Jitter and Wander, and output tolerance. Next time, I will describe the closed-loop gain of the PLL.

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