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LMH6518

Wilson Teo
Prodigy 210 points
Other Parts Discussed in Thread: ADC12D1000, LMH6518, LMH6881, USB2ANY, LMH6881EVAL

Hi,

I'm looking for a variable gain amplifier (programmable) to provide single-end signal to differential signal into high speed ADC (ADC12D1000). Currently, I had shortlisted LMH6518. Can I know if this amplifier will be good enough to optimize the full performance of ADC. I referring to the SNR and noise level.

If not, please provide me with some recommendation and their reference schematic?Can I also know if TI will be able to provide reference design to LMH6518 eval board? I will like to know how the interface should be connected (especially -IN when when +IN is my single ended input signal).

Appreciate your help. Thanks.

  • 0
    TI__Mastermind 22825 points

    Hi,

    The LMH6518 is certainly one option in doing the SE to diff conversion along with digitally variable gain to drive the GigADC's. The newly released LMH6881 is another option. With DC coupling required, these are the only two options that I'm aware of.

    The LMH6518 datasheet shows one method of taking a ground-referenced single ended input to the 2.5V common mode of the LMH6518 inputs using a low noise JFET amplifier. Another schematic in that datasheet shows how to use resistor dividers and pull-up resistors to achieve the same thing, with some insertion loss. There may yet be other methods too. However, TI does not have any evaluation boards to supply.

    Hope this answers your questions? If not, please let me know.

    Thanks,

    Hooman

  • 0 in reply to Hooman Hashemi
    Prodigy 210 points

    Hi Hooman,

    Will the LMH6881 Eval Module comes with the USB2ANY controller? Can I use the USB2ANY controller to control my LMH6518 EVM using the existing GUI?

    Thanks.

  • 0 in reply to Wilson Teo
    TI__Mastermind 22825 points

    Hi Wilson,

    Yes the LMH6881 Eval module comes with the USB2ANY board / controller and necessary cables and software / GUI for download (http://www.ti.com/tool/lmh6881eval).

    The LMH6518 EVM, however, is controlled with its own USB interface board  (http://www.ti.com/litv/pdf/snou007), which you should have received if you ordered the LMH6518 EVM kit (http://www.ti.com/tool/lmh6518sqevk#buy) , and GUI software. I don't think you can use the USB2ANY board to control the LMH6518, unless you develop your own code and cable harness. However, I'm not an expert on these controllers and what it takes to run them :-)

    Is there any particular reason you need to do this? Are there any issues with running the two GUI's on the same PC and using two separate PC USB ports to talk to the two boards?

    Regards,

    Hooman

  • 0 in reply to Hooman Hashemi
    Prodigy 210 points

    Hi,

    I'm doing a design invloving both LMH6881 and LMH6518 which I will like to minimise the number of required connector. I'm hoping that a single USB2ANY controller can allow me to program my design via the SPI control (general) and handling of the CS signal (chipset specific).