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Original question:

ADS54J66: ADS54J66

ADS54J66: ADS54J66:

Yuval Minster
Intellectual 800 points
Part Number: ADS54J66

Thanks for your answers. Regarding answer #4 “The rails were swapped to make the PCB routing easier by removing crisscrossing that would have forced us to use multiple layers”, if the rails are swapped, wouldn’t it change the input signal polarity. I mean, if the input signal is at Max voltage and you swapped the rails, doesn’t the ADC will see it as Min voltage ?

Did you rely on AC signal only when you designed the eval board ?

Any layout recommendations for DC signal as well ? In case of DC - 250MHz signal, does crisscrossing is a must ?

Thanks,

Yuval

  • 0
    TI__Mastermind 20125 points

    Hi Yuval,

    For a true 1:1 acquisition in analog domain, then criss-crossing the input will be required. However, all that criss-crossing does is simply invert the sampled signal. This remains true for DC coupled signals as well as AC-coupled signals. In post-processing, you can digitally invert the signal back to the correct polarity by subtracting the measured code from the max code. I would recommend doing this if possible to simplify the PCB routing.

    Thanks, Chase