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ADAU1701 has Noise but changeing PLL filter will be gone. why?

Question asked by J.Tan on Jun 28, 2013
Latest reply on Jan 28, 2015 by ColemanR

Hello Gens,

 

I have developed a PCB of ADAU1701 with I2S AMP. Everything is good from input analog singal. However, there is noise from ADAU1701.

I found the problem seems from Jitter or somewhere relative PLL. The original PLL filte is 3.3nF, 475ohm and 56nF. The noise will be gone when I remove 475ohm and replaced by a cap 0.1uF. does everyone know the problem from? I set PLL to 256Fs and 12.288Mhz XTAL.

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