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THS4131: Rf and Rg values for fully differential mode

Sahin Okur
Mastermind 27355 points
Part Number: THS4131

Hello HSA team,

I'm building a board using the THS4131 to drive a C2000 ADC in differential mode. In the datasheet, there are recommended resistor values for Rf and Rg for single in/differential out: 

Are these values the same for fully differential mode?

Best,

Sahin

  • 0
    TI__Genius 13935 points

    Hello Sahin,

    Yes, you can use those values for differential to differential operation.  What gain are you using?  Differential in and differential out is the easiest configuration to use.  The input impedance is 2x Rg and you can use series resistors on the amplifier output to set the output impedance.

    Do you plan to use a filter between the amplifier and the ADC?  If not be sure to calculate the noise based on the full bandwidth of the ADC and amplifier ( broadband noise will be determined by whichever has lower bandwidth). 

    We recommend at least a first order low pass filter between the amp and ADC.  Some applications benefit from even more filtering.

    Regards,

    Loren

  • 0 in reply to Loren Siebert 1
    TI__Mastermind 27355 points
    Awesome! My gain is 1, I plan on putting a simple RC filter between the op amp and ADC.

    Thanks,
    Sahin