[time-nuts] femtosecond jitter

[Magnus Danielson]

John,

How where these measurements done?
Also, it looks like you have a systematic component in there, about 80
fs guestimating from the plot creating essentially two tracks up the
slope that is the tell-tale of a sinuoid phase modulation of some source.

Considering the temperature stability that you nicely plotted as a
quadratic shape, it seems like a good thermal stability is needed, which
comes as no big chock.

Can do you do a longer measurement and accumulate the data in a
2D-histogram fashion? That is count occurrences for the amplitude/time
position and then color code it accordingly? That have proved to be a
good tool for analysis.

Cheers,
Magnus

On 04/13/2018 05:54 PM, John Larkin wrote:
> If you walk the differential data and clock inputs of an NB7V52  CML
> flipflop across one another in time, the equivalent jitter is below 20
> fs RMS. That's what we're measuring, but our test rig may well dominate
> the jitter, so the flop is probably better.
> 
> We're using this to test the jitter of some of our timing products, with
> 1/10 the noise floor and 1e-4 times the cost of other ways to do it.
> 
> https://www.dropbox.com/s/1i2yz7otty94o9l/NB7_Jitter_1.jpg?raw=1
> 
> https://www.dropbox.com/s/qahpb8uh1xr53vj/NB7_Steps.jpg?raw=1
> 
> https://www.dropbox.com/s/tpphhi79yxgzy34/NB7_tc.jpg?raw=1
> 
>