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ADS4249: LMH6518 to ADS4249

aronii
Expert 1140 points
Part Number: ADS4249
Other Parts Discussed in Thread: LMH6518, LMH5401, LMH6552, LMH6554

I would like to connect LMH6518 Variable gain amplifier to ADS4249 ADC.

The bandwidth of the signal is DC-50 MHz.

Can you offer any buffer with DC coupling? Please publish a drawing.

  • 0
    TI__Genius 12780 points

    Hi Aronii,

    I am looping in our high speed amplifier team in regard to the DC coupled analog input signal.

    Best Regards,

    Dan

  • 0 in reply to dBrock
    Expert 1140 points
    Hello,

    I see that 7 days passed and no one answered my question so I will try to clarify it:
    In the datasheet and in the evaluation board, all of the input circuits are AC coupled - for RF.
    I got an oscilloscope like application where I must measure DC coupled signals - down to 0 Hz.
    I would like to use LMH6518 which has a 800mV FS span. The ADS4249 has 2Vptp span.
    I need a differential amplifier which can work from +/-5V supplies and amplify the signal by 2.5 at low noise.
    I know a similar device from ADI: ADA4938
    Can you offer a similar device by TI which can do such interface?
    It must have a Common mode voltage input for connecting to the ADC "VCM" output.
    Please offer a component that was tested in such application.
  • 0 in reply to aronii
    Expert 1140 points
    Can anyone help on this issue?
  • 0 in reply to aronii
    TI__Guru* 91947 points

    Aronii,

    Several of the amplifier engineers were on vacation last week. I will forward this request again to them.

    Regards,

    Jim

  • 0 in reply to jim s
    TI__Expert 8300 points

    Hi Aronii, 

    My apologies for the delay in response. The LMH6518 can actually swing up to 1.8 Vpp differential (1.6 Vpp for THD at 100 MHz ≤ –40 dBc). The spec in the datasheet is referring to the single ended output. 

    If you still want to hit the full 2 Vpp range, you can use an FDA such as the LMH6552, LMH6554, or LMH5401 depending on your performance requirements. 

    Regards,