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Entry  Sun Oct 9 10:43:35 2016, Danny Petschke, time difference between 2 channels only ~30-35ps @ 5GSmples/s 
    Reply  Sun Oct 9 11:39:18 2016, Stefan Ritt, time difference between 2 channels only ~30-35ps @ 5GSmples/s 
       Reply  Mon Oct 10 11:30:37 2016, Danny Petschke, time difference between 2 channels only ~30-35ps @ 5GSmples/s allChannels_zero_scaled.pngChn2_Chn3_1ns_delay_scaled.png
          Reply  Mon Oct 10 12:03:27 2016, Stefan Ritt, time difference between 2 channels only ~30-35ps @ 5GSmples/s Screen_Shot_2016-10-10_at_12.01.03_.pngScreen_Shot_2016-10-10_at_12.01.57_.pngScreen_Shot_2016-10-10_at_12.36.48_.png
             Reply  Tue Oct 11 09:04:33 2016, Danny Petschke, time difference between 2 channels only ~30-35ps @ 5GSmples/s 
                Reply  Tue Oct 11 09:20:04 2016, Stefan Ritt, time difference between 2 channels only ~30-35ps @ 5GSmples/s 
Message ID: 546     Entry time: Tue Oct 11 09:04:33 2016     In reply to: 545     Reply to this: 547
Author: Danny Petschke 
Subject: time difference between 2 channels only ~30-35ps @ 5GSmples/s 

Hello Stefan,

thanks for the paper. That makes sense. I thought about sth. like that but wasn`t sure. Couldn´t check higher frequencies (limit of my function generator).

What do think about the other picture I attached yesterday where Chn1 shows a totally different offset than Chn2-4. Moreover Chn4 shows some streaks (red circle) ?

Best regards

Danny

Stefan Ritt wrote:

Ok, I got it. The timing resolution is affected by the signal-to-noise ratio over the rise-time of your signal. You find the full formula herer:

https://arxiv.org/abs/1405.4975

Your sine wave input signal has a slow rise time, and therefore limits the time resolution. I reproduced your measurement with a 20 MHz sine wave and got the same result:

 

If I increase the frequency to 100 MHz and increase the amplitude, I get a better resolution:

 

This is 5 ps which is better than 37 ps, but still not 2.5 ps. This can only be reached by sending single pulses to the evaluation board which have a rise time of > 300 mV / ns, which can be seen here:

 

It is important to understand the relation timing - resolution vs. rise time / noise as explained in the quoted paper. If you have tiny pulses from your detector, you never will be able to measure excellent timing. This is physics, and not related to the specific electronics you are using.

Best regards,
Stefan

 

 

 

 

 

 

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