AD8047 problem

Hi ,

Im using AD9744 DAC for one of my project and AD8047 for I_V converter for that DAC. Im getting output voltage twice the Input to adc fron AD8047.

Can anyone tell me how to connect onli one OUTA to AD8047.

Regards,

Bhavya

SCHEMATIC156.pdf
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  • Hello Bhavya,

    I would suggest a step-by-step check with a scope, starting at the transformer secondary, then move on to the AD8352 input, its differential output, then AD9455 inputs. Once you are sure that there are no glitches on the input side, you can write test programs for generating known words at known frequencies, feeding these to AD9744 and probing through at each node, to the AD8047 output. If the hardware does not show any glitches for the test programs, then you will know for sure that the problem lies in your code. If there are glitches for the test programs as well, it could be a layout or component selection related issue.

    Have you done signal integrity tests for your PCB layout?

    Lower frequency response will solely depend on your RF Transformer characteristics. I doubt whether this will be feasible, though.

    Hope this helps,

    JayantD

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  • Hello Bhavya,

    I would suggest a step-by-step check with a scope, starting at the transformer secondary, then move on to the AD8352 input, its differential output, then AD9455 inputs. Once you are sure that there are no glitches on the input side, you can write test programs for generating known words at known frequencies, feeding these to AD9744 and probing through at each node, to the AD8047 output. If the hardware does not show any glitches for the test programs, then you will know for sure that the problem lies in your code. If there are glitches for the test programs as well, it could be a layout or component selection related issue.

    Have you done signal integrity tests for your PCB layout?

    Lower frequency response will solely depend on your RF Transformer characteristics. I doubt whether this will be feasible, though.

    Hope this helps,

    JayantD

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