We just bought VRTS 1.5 Demo Board and tried todo the bode plot for the output of the board ,
Figure1: shows the setup and everything is setup in accordance to the guidelines provide by siglent in the link below. Measuring Power Supply Control Loop Response with Bode Plot II - Siglent (siglenteu.com)
The issue is with the bode plot of channel2 , i am getting the following bode plot when i set switch 1 and 3 on .
and get the following with switch 2and 3 on
and the following with either all of or one of them on .
I am not so sure about the bode plot and the switches because the closest i get to the given result (i.e., provided by siglent) is when i have switch 1 and 3 on and on the data sheet it says 1 is too high for Non-invasive Stability Measurement . So i am not sure if i am missing something out or the results i am getting are expected for the board under test.
(*Note: i have checked my probes and and everything seems about right with the configuration of the bode plot and i am generating the wave internally)
Thank you steve, I will copy and paste the post on the mail and it would be great if you could send me your results with the specification of the test like (amplitude , and other settings of the oscilloscope ) so i can recreate it on my end . thank you so much
I can't see settings, like the signal injection amplitude, or calibration. The measurements in the app note you linked were not measured by us, and you can see in some of the measurements there was significant overdrive.
What I can do, is I can measure a board here using a FRA and see if these are inline with your measurements. I can see what is important to take away from your measurements and that is that the ceramic capacitor has much worse stability than the aluminum or combined capacitors and also that the load current impacts the stability as well.
If you write to me at email@example.com, I can provide you with my measurement results as soon as I do the measurements