Period Jitter vs. Phase Jitter

Question

I've got an oscillator spec that states an RMS period jitter of 1.7 ps and an RMS phase jitter of 0.85 ps.

I know that period jitter describes the deviations from the oscillator's average period over a number of randomly selected cycles, I'm not sure how to interpret the phase jitter. Apparently, it is defined as the integration of phase noises over a certain spectrum.

This raises a number of questions:

• is the phase jitter just another view of period jitter or does it contain unrelated information?
• why should I care about that number?
• is it a coincidence that phase jitter = 1/2 period jitter?

Answer 1

Phase jitter and period jitter are simply rms summations of jitter over different bandwidths. There is little standardisation on what bandwidths are involved.

If the equipment maker is reputable, then they will define the bandwidths used, either in their documentation, or in supporting documentation on their website.