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ADS7883 Evaluation Module (ADS7883EVM): bypass the input circuit

Enrico Santagati
Prodigy 60 points
Other Parts Discussed in Thread: ADS7883EVM, ADS7883, THS4031

Hi all,

I am using the ADS7883EVM as a prototype board to include the ADS7883 in my design.

At this point, I would like to get rid of the analog part of the board, and use the digital part only with external (out of the board) analog components. Specifically I was wondering if I can by pass the input circuit (including the input low noise amplifier), to feed the ADC through an external low noise amplifier. 

What is an easier way to do that?

Thanks,

Enrico

  • 0
    TI__Genius 9975 points

    Hello Enrico,

    You could potentially do away without using the THS4031 on the EVM board; the decision depends on the quality of your signal source and whether it can drive the ADS7883 properly.

    My recommendation would be to first do a round of data collection using the full EVM (with its analog front end) and see what kind of performance you get as a baseline. The driving circuitry in the EVM is selected to ensure that, even if you use a high impedance source (greater than 300 ohms), the THS4031 will buffer it and drive the ADS7883 properly.

    After that, you could remove R25 and blue-wire your input to C20. By comparing the data obtained both ways you can determine, based on whether performance suffers significantly, if you really need the input circuitry.

    Hope this helps.

    Best regards,

    Jose

     

  • 0 in reply to Jose Duenas
    Prodigy 60 points
    Thank you very much, Jose.

    I need a low power amplifier in my design, but I need much more gain than the one offered by the THS4031. I've selected another amplifier with higher gain but similar characteristics to the THS4031.

    I will try first with the THS4031 alone, than having both, and finally I will see if I can remove the THS4031. I am very space and energy constrained in this project, so I can't afford having unnecessary components.

    Thank you again,
    Enrico