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Using AD9177 to output single-tone frequency, configured in Main Path NCO Only Mode, abnormal output

Category: Hardware
Product Number: AD9177

When I use the AD9177 to output a single-tone frequency, configured in Main Path NCO Only Mode, with the DAC clock in direct input mode at a frequency of 9600MHz, and the DDS configured at 1/16, the expected output is 600MHz. However, the actual output is as shown in the following figure. The register readback information of the configuration is shown in the figure.

No matter how I adjust the frequency word, the output spectrum remains unchanged. If I modify the clock frequency to 8000MHz, the output spectrum will include frequencies such as 2000MHz and 4000MHz. What is the problem, and how can I solve it?

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  • Hello, it looks like the FTW is set as 0x0100000000. I think you are off by 1 hex position to get 1/16 Fout. Try setting 0x1D0 to 0x10 instead of 0x01.

    Register 0x090 reads back 0xEE which implies that all dacs are powered down except for dac0. Are you looking at the dac0 or the dac1 output? The log says dac1, but maybe you are indexing differently? I cant see any paging of 0x1B to clarify which dac values are being read back. 

  • Thank you for your reply. I am using the DAC0 channel output, and the new image describes the output spectrum of channel 1.Channel 1 is closed, so there is no output, which is normal.

    The  frequency word was modified. However, the output of DAC0 remains unchanged, just as it was before.

    When I change the clock frequency to 4.8GHz and 2.4GHz, the output is as shown in the figure.

    The register read-back results and the schematic of the analog output circuit are shown in the figure.

    What other methods can I try to solve this problem? Thank you."

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  • Thank you for your reply. I am using the DAC0 channel output, and the new image describes the output spectrum of channel 1.Channel 1 is closed, so there is no output, which is normal.

    The  frequency word was modified. However, the output of DAC0 remains unchanged, just as it was before.

    When I change the clock frequency to 4.8GHz and 2.4GHz, the output is as shown in the figure.

    The register read-back results and the schematic of the analog output circuit are shown in the figure.

    What other methods can I try to solve this problem? Thank you."

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