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ADAU1701 DAC output filter if using differential-input amps?

Question asked by MCastany on May 7, 2014
Latest reply on May 8, 2014 by MCastany

Hi,

 

For a DSP-based project, I am using the four DACs of the DAU1701 to drive two amplifiers in BTL mode, using SigmaStudio for making the differential outputs. The amplifier's input is AC-coupled with a 1uF cap, creating a high-pass filter with the input imedance.


Because of the ouput signals of the ADAU are differential, I was wondering if the DAC output filters need to be implemented anyway to avoid strange demodulation noises (Figure 18 of the ADAU1701 datasheet, the passive output filter, page 22).

 

If so, can they be implemented without the 47uF cap, as the 1uF of the amp's input is blocking DC? (The amp input DC bias is 2.5V,1V greater than the ADAU).


Best regards,

 

Marti

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