the question about DAC of ADAU 1701_SigmaDsp(datasheet)

The DAC pass_band  filter response is over 20Khz( in figure 10), while the DAC  stop_band filter response is only over 2Khz(in figure 11) , who wants tell me why the gap is so large?

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  •      Hello,

         Evidently this is a typo in the datasheet.  Figure 11 intends to show the filter's response above the audio range, so its 0 -- 20 KHz axis is in error.  For example, it would make more sense if drawn like this:

    The important fact is, the filter is more than enough for its job.  Thanks to this DAC reconstruction filter, all we need after the DAC is a simple RC filter specified in the datasheet.

         Best regards,

         Bob

Reply
  •      Hello,

         Evidently this is a typo in the datasheet.  Figure 11 intends to show the filter's response above the audio range, so its 0 -- 20 KHz axis is in error.  For example, it would make more sense if drawn like this:

    The important fact is, the filter is more than enough for its job.  Thanks to this DAC reconstruction filter, all we need after the DAC is a simple RC filter specified in the datasheet.

         Best regards,

         Bob

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