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ADS7946: SNR & SINAD plots out to Nyquist frequency @ 2 MSPS

Mark Lanciault1
Prodigy 160 points
Part Number: ADS7946
Other Parts Discussed in Thread: ADS7945,

For SNR & SINAD performance @ 2 MSPS  the data sheet lists performance only at 20 KHz input frequency. Are there plots for these out to Nyquist frequency (~1 MHz)? I would like to see how these parameters degrade as input frequency increases. Also, what is the input level for these measurements? If new data needs to be taken, please do it at full-scale input.

  • 0
    TI__Mastermind 25030 points

    Hello, Let me look into this

    Regards

    Cynthia

  • 0 in reply to Cynthia
    TI__Mastermind 25030 points

    Hello,

    unfortunately, we do not have data out further than what is available in the datasheet. The typical specification should be used in this case. 

    Regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 160 points

    How do I escalate this to to get this measured?

  • 0 in reply to Mark Lanciault1
    TI__Mastermind 25030 points

    Hello,

    Apologies for the late response

    Please reach out to your TI representative, be it sales or field apps, and they should be able to escalate this internally 

    Regards

    Cynthia 

  • 0 in reply to Cynthia
    Prodigy 160 points

    Thanks, but I tried that and got stonewalled saying all the have is SNR & SINAD for the low frequency inputs and that's what I'll have to use. I guess they aren't interested in publishing the performance out to Nyquist, which now makes me question the performance. At this point I am just wondering how the parameters degrade as the input frequency increases - can I at least get some info on that, even if anecdotal? With such resistance to publishing it, I fear is gets bad real quick which would make me consider other devices. I'd hate to make that judgment due to a non-response. Is there anything I can get on this?

  • 0 in reply to Mark Lanciault1
    TI__Mastermind 25030 points

    Hello Mark, 

    I apologize, that is frustrating. I believe that the limited test data is not due to performance degradation not reflects that there is performance limitation being hidden, but more related in efforts to save on test time and resources. 

    I propose to collect data on the EVM and upload it in to an SNR calculator to prove to yourself that the device works.

    I can have the ADS7945EVM sent to you, with a ADS7946 sample to switch on the board (or you could use the ADS7945 that is on board).

    TI also has an Analog Calculator that can calculate the SNR from the data points collected

    Regards

    Cynthia

  • 0 in reply to Cynthia
    Prodigy 160 points

    Hi Cynthia,

    Perhaps I am dating myself, but can remember a time when all ADC vendors supplied performance in a graph for SNR and SINAD out to Nyquist as part of their standard datasheet, albeit with specific superior points/scenarios called out in a table to catch an engineers eye. I appreciate the offer of am EVM, but we are a small company and I can't take the time to run the data that is needed. Thanks again.

    Mark