TM4C1294NCPDT: ADC analog bandwidth

Getting to 4Msps requires trickery with two A/Ds.

There is, as is often the case, a reason bandwidth is not quoted. Besides the sampling rate issue bandwidth is determined as much by your signal conditioning as the maximum sample rate and also by the S/W. If you sample at only 200Hz then that will limit your bandwidth well below what's achievable at 2Msps.

What the maximum rate does give you is an upper limit on your attainable bandwidth. By Nyquist your sampling rate must be greater than twice the highest frequency in your signal. By reversing that relationship you can see that for a 4Msps rate your signal maximum bandwidth must be less than 2 MHz. Practically speaking you would not likely want to push that limit.

Now work out the bandwidth of your signal:

martins liepins said:

I need to capture 30 ns pulses using stroboscopic receiver

If it's a sinusoidal wave then that is an ~17MHz signal. It's likely a single rectangular pulse in which case a quick rule of thumb would suggest closer to 170MHz, depending on the fidelity of capture you require it may  greater bandwidth.

Robert