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DAC3283 Data Rate

Stuart Abrams
Prodigy 10 points

Other Parts Discussed in Thread: DAC3283

I am currently using the DAC3283 with the following expectations:

(1) DACCLK = 737.28 MHz

(2) DATACLK = 184.32 MHz

My question is, if I want to run I/Q samples into the DAC and use the Fs/4 coarse mixer, do I need to send the samples in at 368.64 MHz due to the fact it takes 2 cycles to get the I and Q samples in?  Is there any way of supplying only real samples to the DAC and utilizing the Fs/4 coarse mixer?  Any help would be appreciated.

 

Thanks,
Stu

  • 0
    TI__Guru* 81425 points

    Stuart,

    The DATACLK frequency will depend on the data rate and interpolation filters being used.

    Your concept of having 2 DATACLK cycle to latch in the I/Q sample is correct. For 1x interpolation, the DATACLK will be 2x of the DACCLK. For 2x interpolation, DATACLK will be 1x of DACCLK. For 4x interpolation, the DATACLK will be 1/2 of the DACCLK. Please see attached pdf for detail.

    Due to the nature of the Fs/4 mixing algorithm, the Fs/4 mixing process will mix both A and B input samples onto the A and B output. (i.e. Aout = A, -B, -A, +B; Bout = +B, +A, -B, -A). Therefore, the Fs/4 mixing does not allow dual channel independent real sample upconversion. The only way to do so is to use Fs/2 mixing, which does not mix A/B channels together. 

     

    -KH

    DAC3282-3 Byte Wide DDR Clocking.pdf