Phase Noise to Jitter Conversion & Relationship

- notes and details about the relationship between phase noise & phase jitter and the conversion process and techniques.

Phase noise tutorial includes:

    •  Phase noise basics
    •  Phase noise / jitter relationship
    •  Phase noise specifications
    •  Phase noise measurements

Phase noise and phase jitter are two ways of looking at the same parameter of a signal.

In view of the fact that they are linked it is necessary to have an understanding of exactly what each one means, and the phase noise to jitter relationship and conversion.

Both formats: phase noise and phase jitter have their uses and are equally valid but are easier to use in different applications..

Phase noise & phase jitter

Phase noise and phase jitter are both ways of describing what is effectively the same parameter. Phase noise describes the performance in the frequency domain, whereas the phase jitter performance in the time domain.

The choice of which domain to use depends upon the application and the way the figures are best expressed.

Typically for RF applications such as signal sources and systems used for transmission and reception of digital signals (including satellite systems) phase noise, i.e. frequency domain is the normal method used.

However for applications such as TDM (time division multiplexing) systems will be interested in phase jitter far more as poor jitter performance can result in data clashes and an increased number of data re-sends.

However it is not unusual for the phase jitter performance of an RF system to be quoted in terms of phase jitter. Under these circumstances it is necessary to understand the phase noise / phase jitter relationship, and to be able to apply a phase noise to phase jitter conversion.

Phase noise and phase jitter units

Phase noise and phase jitter are measured using different units as they are parameters using different domains.

• Phase noise:   Phase noise is typically measured in dBc/Hz at a given offset from the carrier. This is the noise power in a 1 Hz bandwidth at the offset from the carrier.
• Phase jitter:   Phase jitter is measured in radians rms. This indicates the angular jitter from the steady carrier.

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