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ADAU1701 eval board measured noise (graph)

Question asked by AriLunden on Feb 1, 2013
Latest reply on Feb 1, 2013 by AriLunden

Hello,

 

I measured the idle noise (inputs grounded) of the board I designed and compared to ADAU1701 evaluation board. The code in both just connects the inputs directly to outputs. I was surprised how big difference there was between those two and I'm wondering now if the measurement is good.

 

Can anybody comment if the measured noise curve is most likely correct or not?

 

I also wonder if that 1/f noise which is best visible in red curve between 20Hz and 1kHz comes from DAC or from somewhere else? Not that it's really a problem, just curious.

 

CYAN curve: evaluation board + USB power

GREEN curve: evaluation board + battery power

RED curve: own board

 

Thanks,

Ari

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