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how much sample rate and bandwidth do i need for this waveform?

Ras Sharif50
Genius 3455 points
Other Parts Discussed in Thread: ADC3221

Hi Everybody,

please consider the bellow waveform:

there is two of the above signal which should to be sampled simultaneously.

i am selecting an ADC converter.

i need to know the bellow characteristics:

1) Bandwidth

2) Sample rate

3) type of interface ( to MCU )

Best Regards

Ras

  • 0
    TI__Guru**** 175201 points
    Hi Ras,

    This is an unusual question. Are you looking to try and capture the entire waveform above, including details on the rise and fall edges? If so, you would need to provide considerably more detail on the waveform and it would most likely need to go to our high speed ADC team.
  • 0 in reply to Tom Hendrick
    Genius 3455 points
    Hi Tom,
    thank you for the reply.
    yes, it is required to sample the entire waveform.
    which detail does it need?

    Regards,
    Ras
  • 0 in reply to Ras Sharif50
    TI__Guru**** 175201 points
    Hi Ras,

    At a minimum, the expected dV/dT of the rise and fall times of your waveform. Your screen shot looks like it has 19 (let's call it 20) steps to reach 100% (of what voltage? 0-5?) and it looks like 2x that for the falling edge. By Nyquist, you need a minimum of 2x sampling speed to reproduce a sampled signal, but for any sort of accuracy, you are looking at 10x or better. So, you are looking for something at least 1/risetime x10 sampling speed. Magnitude of the signal is important and the expected resolution is also important. What is the repetition time of this pulse? That will also influence your decision in what ADC to choose.
  • 0 in reply to Tom Hendrick
    Genius 3455 points

    Hi Tom,
    Thank you for the answer.

    rise and fall times are 1 and 2 us respectively. rise time is more important.
    the voltage is design-able in the analog section. ( ie 0-1 V, 0-3V, ... )
    10 bits of resolution seems suitable.
    the signal doesn't repeat any more. it takes place one time.

    i achieved to 20 MSPS ( for two channels ) for now.

    it remains two questions:
    1) analog bandwidth
    2) interface

    Regards,
    Ras

  • 0 in reply to Ras Sharif50
    TI__Guru**** 175201 points
    Hi Ras,

    Let me send you over to the High Speed data converter team. They should have something to satisfy your application needs.
  • 0 in reply to Tom Hendrick
    TI__Genius 12780 points
    Hi Ras,

    If you need a dual channel solution, you might want to look at the ADC3221 12 bit 25 MSPS.

    Best Regards,

    Dan