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ADS54J60: ADS54J60(ADC)response improvement

shivakant dwivedi
Intellectual 960 points
Part Number: ADS54J60

Hi,

I am using ADS54J60 for one of our application.

i am receiving 40 MHZ base band signal while doing sampling at 500 MSPS (with out enabling internal filter):

Results are as fallows on wave vision:

I want to know why noise floor coming like Bow instead of flat?

i am also getting harmonics @ 80 MHz,120 MHz.

Anti aliasing filter cut off frequency is 280 MHz

Is there any harmonics/noise improvement through this IC internally?

  • 0
    TI__Guru* 91947 points

    Shivakant,

    Are you using an ADS54J60EVM connected to an older National Capture card and running Wavevision? If so, this is a setup we have never tried before. Normally this EVM is tested with a TSW14J56EVM. Can you send the register settings for the ADC? If this the TI EVM, send the LMK settings as well.

    Regards,

    Jim  

  • 0 in reply to jim s
    Intellectual 960 points
    Hello Jim,
    I am not using ADS54J60EVM .
    I designed a board in which i am using this IC which is interfaced with FPGA.
    Data coming from ADC is getting captured in a .bin file & i am plotting this data in wave vision.
    Please find the register setting for the above ADC:

    0x0000, 0x81
    0x4001, 0x00
    0x4002, 0x00
    0x4003, 0x00
    0x4004, 0x68
    0x60F7, 0x01
    0x6000, 0x01
    0x6000, 0x00
    0x0011, 0x80
    0x0059, 0x20
    0x0054, 0x80

    0x0053, 0x01
    0x0053, 0x00
    0x0053, 0x01
    0x0053, 0x00

    0x0054, 0x00

    0x4003, 0x00
    0x4004, 0x69

    0x6000, 0x80

    0x4003, 0x00
    0x4004, 0x6A

    0x6017, 0x40

    0x6017, 0x00

    0x4003, 0x00
    0x4004, 0x68

    0x6000, 0x01
    0x6000, 0x00

    0x4003, 0x00
    0x4004, 0x69
    0x6006, 0x1F

    0x6002, 0x00

    0x6005, 0x00

    0x6007, 0x00
  • 0 in reply to shivakant dwivedi
    TI__Guru* 91947 points

    Shivakant,

    I tried your settings with our EVM using the on-board VCXO  for one test and an external 500MHz for another test. In both cases the results looked fine. Are you using a filter on your analog input? How clean is your clock source?

    Regards,

    Jim

    ADS54J60_Fs_500M_IF_40M.pptx

  • 0 in reply to jim s
    TI__Guru* 91947 points
    Also make sure to give the ADC a hard reset after the clock is present but before you program the registers.
  • 0 in reply to jim s
    TI__Guru* 91947 points
    Shivakant,
    Are you still having issues with this? If not, I would like to close this post.
    Regards,
    Jim