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ADS5401: ADC aperture delay?

Part Number: ADS5401

Hi,

What is the aperture delay - sampling clock rising (?) edge to the time when the actual sampling occurs, normalized to the input pins (actually balls)?  Can not find any related data in the datasheet besides 100fs rms aperture jitter. Is it reasonable to expect the delay stay more or less the same when sampling frequency changes and not subject to much variation between pin compatible parts (ADS540x) with different performance (500-800 Msps max)?

Regards,

Alexey

  • Hi Alexey
    I have referred your question to the ADS5401 expert. He will provide a more detailed response soon.
    Best regards,
    Jim B
  • Since 100fs is the characterized aperture jitter at 800MSPS, it is safe to assume that the aperture jitter will improve at frequencies lower than 800MSPS.

    Yusuf
  • Hi  Yusuf,

    I am asking about the aperture delay from the sampling clock input to the actual sampling moment. I can not find it in the ADS5401 datasheet, so it is probably not characterized unlike for other TI ADCs. for example:

    Here is the definition from the same datasheet to make sure we are talking about the same thing:

    1. Do you understand the question?

    2. What edge of the input clock is used to sample data (positive or negative)?

    3. Could you provide the spec for the ADS5401 (and other compatible ADS540x ADCs) aperture delay? If not that are the expected "typical" values?

    Regards,

    Alexey

  • Alexey,

    Gotcha. Sorry for the confusion. If the aperture delay isnt in the datasheet then i'll need to ping a design engineer that worked on the part. I'll have to get back to you. The input signal is sampled on the negative edge of the clock signal.

    I will get back to you as soon as i hear from my contact.

    Thanks

    Yusuf
  • Alexey,

    Unfortunately the design engineers do not have the aperture delay spec for the ADS5401.

    Yusuf

  • Yusuf,

    Is any way TI can help me resolving this issue more effectively than buying evaluation board, characterizing part myself, not expecting too much variations in production parts, etc...

    Regards,
    Alexey
  • Hey Alexey,

    Sorry i have been on vacation. Thanks for your patience. I will be taking the next couple of days to try and measure this on my end. Sure there will be part variation but hopefully i can give you a ballpark.

    Thanks

    Yusuf
  • Hey Alexey,

    Sorry this is taking so long. Measuring this on the EVM has proven to be a little more difficult then intended. I hope to have the test report completed this week.

    Thanks

    Yusuf
  • Hey Alexey,

    Due to limited bandwidth I will need a lot more time to complete this measurement. Would it benefit you to send you an EVM free of charge as soon as possible to do the measurement on your end? If so, send me your address offline. I sent you a friend request.

    Thanks

    Yusuf