Dear Don,
I "solved" the problem by using a more abrupt output LPF .
The 1 Vpp noise previously described was directly measured on the output of the codec. Therefore, after reading the following work: http://www.ti.com/lit/an/sbaa055/sbaa055.pdf , I observed the noisy signal in the spectrum analyzer and the measured noise , despite seem excessive in the time domain , conformed to the expected limits.
Likewise , the power consumption despite being higher than in the previous prototype codec , also is within the allowable limit.
Therefore, I used at the output of the codec a LPF with lower cutoff frequency and higher order , and the noise was removed in the output signal .
Regarding the source of the interference , we found that BCK bit off , the noise disappears. Also, the interference has the same frequency as the BCK signal , we noticed that we were both related effects .
We contemplate that for this prototype the problem was solved . But for future prototypes of the system we want to know if we have any particular consideration in order to minimize this interference.
Thank you very much .
Best regards,
Alejandro Uriz