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TLV320DAC3100: DAC modulator noise

Mochi
Genius 4195 points
Part Number: TLV320DAC3100


Hello,
We observed unique noise from DAC modulator on the proto typing unit and verified it on EVM. 
When we inputted low level sine wave signal such as -60dB, -70dB then DAC generate in-band noise as attached FFT waveform.
Here is the working condition: Fs 48KHz, PBR1, DOSR 128.
Is there any workarround? Adding AC dither or changing OSR? 
Regards,
Mochizuki
DAC3100 -60dB.jpgDAC3100 -70dB.jpg
  • 0
    TI__Genius 15170 points

    Hi,

    We expect to see an increase in the noise floor above the Nyquist rate (1/2 of the sample rate) as that is how the delta-sigma modulator works, it pushes noise into these frequencies above our hearing range and above the Nyquist rate. The device is designed for a flat bandpass between 0 and 20kHz at 48kHz sample rate.

    Best,
    Mir