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ADC12J4000EVM: DC coupling input

Apurva Gowda
Prodigy 220 points
Part Number: ADC12J4000EVM
Other Parts Discussed in Thread: LMH5401EVM

Hi,

We are trying to use the ADC12J4000EVM board to sample a pulse train and thus require the information at DC. However, the evaluation boards are AC coupled through a balun. Is there a simple way to convert this into a DC coupled input?

Thank you,

Apurva Gowda

  • 0
    TI__Mastermind 44560 points

    Hi Apurva

    Please download the ADC12J4000EVM design package documents, available from a link in the EVM product folder here:

    http://www.ti.com/tool/ADC12J4000EVM

    The default input path is via VIN through balun T1 and ac-coupling capacitors C3 and C5. The board can be configured for dc-coupled differential input by removing capacitors C3 and C5, and installing 0-ohm resistors at C1 and C6.

    The applied differential signal must meet the input common mode requirements of the ADC. The best way to achieve this is to use the signal available at pin 2 of the Vcmo connector to bias the common mode voltage of the external DC-coupled differential signal source. If your signal source is not already differential, you could use an amplifier to provide single-ended to differential conversion of your signal. Something like the LMH5401EVM could be used.

    I hope this is helpful.

    Best regards,

    Jim B