Normalizing dynamic range of 12 bit AUX input to match 24bit codec audio

Discussion created by LarsHaagh on Nov 10, 2015
Latest reply on Mar 30, 2016 by DaveThib

Hello Dave - or other SigmaStudio oracles


My design is built around an ADAU1452 with two AD1938 codecs for audio I/O.  This part of my design works fine. I've also routed two of the AUX ports on the ADAU1452 to audio input ports. I realize these are only 12 bit in resolution, which however, is fully sufficient for some of my analog signals.

I have been struggling with getting sound from the AUX inputs, and after checking waveforms all the way up to the ADAU it suddenly dawned on me today, that I'm mixing 12bit audio with 24 bit audio. No wonder I'm seeing ~70dB attenuation on my AUX ports.


Question:  How do I expand the 12 bit input to utilize the full 24 bit dynamic range and match the dynamics of my high quality audio from the codecs ???


Thank you for your support !!


Best regards,