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DAC38J84EVM: DAC38J84 - SFDR out of specifications

lionel rodriguez
Prodigy 30 points
Part Number: DAC38J84EVM
Other Parts Discussed in Thread: DAC38J84

Dear,

I bought the dac38J84_evm board to bench my project. 

But the SFDR is very bad -48dBc (hd2)

Setting :

JESD204B - 6.144Gbps

Sample rate 614.4 MSPS (FPGA)

Interpolation : 2

DAC sample rate : 1228.8 MSPS

Output fréquence : 20MHz (same problem with different frequencies)

Internal oscillator 

Could you help me to solve this problem ?

Regards

Lionel 

  • 0
    TI__Guru 65884 points

    Hi Lionel,

    If you change the output frequency to be about 70MHz, please advise if you can see better HD2. Please also post screen captures from your spectrum analyzer. The performance measured on the EVM should be close to Figure 4 of the datasheet since the datasheet plots are taken from the EVM.

    Most likely you may need to adjust the dynamic range, attenuation settings, and RBW of your analyzer to avoid analyzer front end saturation. Please also refer to your spectrum analyzer user's guide for the optimal settings given the DAC's output power.

  • +1 in reply to Kang Hsia
    Prodigy 30 points

    Hi Kang

    Excuse me for the delay.

    It was a bad parameter inside my code.

    Thanks for your answer

    Regards.

    Lionel