Thanks Raanan

The relationship between BW and rise time is fixed. I am not sure I follow your comment. Can you be more specific? The application, some numbers?

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This is ( a textbook theoretical situation) for a fixed signal that is then averaged. Who is interested in that? In any practical use the signal is changing.

@@sambenyaakov That is rather my point. Practical signals require significantly higher sampling rates than the Nyquist criterion... 4-5 times faster gets reasonable response times.

@@byronwatkins2565 Isn't that what I am saying in the video?

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Thanks for input. Not only that this is possible it is done very successfully. In the products that we have designed, the signals are sampled synchronously. Not that difficult to accomplish.

@@sambenyaakov I wasn't claiming it wasn't possible, but if you look at precision A/D convertors from TI and Analog Devices, the app notes mention this subject exactly 0 times and I can assure you that outside of your community, this isn't even discussed. So synchronizing the frequency of the A/D with the SMPS is rare and adjusting the phase relationship to coincide with a quiet portion of the SMPS is unheard of. See for example Analog Devices app note CN-0137 where they discuss using a SMPS solution to increase efficiency for a precision A/D converter. In their circuit example, they don't even bother hooking up the switching frequency control. Or TI's Application Report on High Speed A/D Convertor Basics, where half of the long document is allocated to input signal conditioning without a single word about SMPS synchronization. I suspect that somewhere on these sites you would find this discussion, but that the overwhelming percentage of designers has never seen it.

@@ats89117 I agree with professor. At my university in Poland and in the industry that I worked with using synchronous sampling is common practice. The app note you refer to is about ADC power supply, not application in power converter and that's why this information is missing. What systems are you familiar with? Are they equipped with microcontroller?

@@tomaszswiechowicz1181 The question is not about synchronizing the sampling frequency of the SMPS with the A/D converter. Many SMPS have a clock frequency input for synchronization. The question is about phase shifting the convert time to ensure that it occurs while the SMPS is at it's least noisy period. My application area is phased arrays where there are 10 to 1000 A/D converters each bringing in 1-2 million samples per second with 20 bits per sample. These systems are always controlled by FPGAs and the SMPS is frequency locked but I've never seen it phase locked. If there was a phase adjustment, which could certainly be added to the firmware, the only way to do the adjustment would be by trial and error because there is no visibility on the delays for either the SMPS or the FPGA clock circuit that generates the convert signal. I am designing one of these systems right now and have added this as a requirement because it seems like it could be very important. As an aside, thanks for your comment. I have a friend who is a professor at the University of Warsaw, and I am interested if this is a more visible issue in other places...

@@ats89117 I think that my misunderstanding came from the fact that I'm designer of power converters (based on microcontrollers) and adding phase adjustment functionality is trivial. Looking at the market, however, I can't recall any SMPS IC capable of that. Maybe ICs for converters in interleaved configuration would have it. I have a fact that might be interesting to you: I built reactive power compensators that are supposed to work in parallel through fiber optic communication. One of my goals was to enable phase adjustment through it, because it greatly reduces conducted EMI below 1MHz when phase is selected for destructive interference.

You add AC analysis instead of transient.

@@getusel Ok. And what source to set for 'small signal AC analysis'?

@@RogueTuning Right click to any independent source select advanced from the resulting window. Choose the source from the function menu. On the right side of the window you will see Small signal Ac analysis amplitude box. Insert 1 there and you should be able to run ac analysis.

I do mot like the TI Pspice. It is missing parts and the library is meager. Have you tried Qspice?