Hi Sergio,
It looks like you are doing the right thing to remove the DC offset - not sure why it did not work.
I'm going to move this post to the audio converters forum where they can take a closer look.
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The AIC3204 has certain signal processing blocks available which can be used to removed the DC offset. These block include: (1) 1st order IIR; (2) some number of biquads, and (3) an FIR. See Section 5.10 of the attached doc. Key items in this section are:
- Depending on the targeted performance, the decimation filter type (A, B or C) and OSR value can be determined
- Based on the identified filter type and the required signal processing capabilities the appropriate processing block can be determined from the list of available processing blocks (PRB_R1 to PRB_R18) (See Table 5-4).
The signal processing block configurations are described in Section 5.8.1 of the AIC3204 datasheet.
For example, if PRB_R5 is selected, then in addition to Filter A (decimation), 5 biquads and a 1st order IIR are available. In this case, the 1st order IIR alone might be sufficient to remove DC offset. If not, a biquad could be added.
Regards,
Mark