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DAC38J84: Interpolation configuration

yifan zhu
Intellectual 255 points
Part Number: DAC38J84

Hi:

Im currently running DAC 38J84 and I'm running at an output data rate of 368.64MSPS. I want to know when I enable interpolation function, what else should I do except configure the first register(0x00) to set the factor of interpolation? And when I'm sending a bitstream, I did a FFT on the received data and I find that the frequency response is not flat (looks like there is a sinc filter on the frequency domain), how could I get a flat frequency response?

Thanks

  • 0
    TI__Guru* 91947 points

    Kevin,

    If you were interpolating by 1 then switched to 2, you would have to do the following:

    1. Change DACCLK to run 2X faster.

    2. Write to config0 0x0118 to set new interpolation rate.

    3. Write to config37 0x4000 to change the JESD CLK Divider since the DACCLK changed..

    4. Write to config59 0x800 to change Serdes reference divider since the DACCLK changed..

    5. Write to config31 a 0x9980, then 0x9982, then 0x9980 to perform a SIF Sync.

    To improve on flatness, enable the x/sin(x) function by writing to config0 and setting bits 0 and 1 to a '1". make sure to back off on your input power after enabling this if your output is saturated. See the data sheet for more info regarding this feature.  

    Regards,

    Jim

  • 0 in reply to jim s
    Intellectual 255 points

    Hi: I'm not really sure what is this SIF Sync mean...and when I change the interpolation factor, I should just remain the original jesd lane rate right? (Since Im running a 368.64MSPS output rate, my jesd lane rate is 3.6864Gbps, operating at 8 channel mode)