Questions about the PCM4204:
1) The datasheet only provides a typical full scale input voltage of 6Vp-p with no upper or lower limits. Is there any data available on full scale input voltage variations lot-to-lot, or at least the worst case minimum full scale input voltage?
2) Noise shaping can explain the rising high frequency noise floor above 50kHz in the 192kS/s FFT plots on datasheet page 12. What explains the steeply rising (about 40dB/octave) low frequency noise floor below 70Hz in the 192k plots? It's not present in the 48k or 96k plots.
3) Curious about the chip architecture - if the modulator reference voltage is 3V, why is the common mode voltage 2.5V (1/2 Vcc) instead of 1.5V (1/2 Vref)?