Hi, Team
Customer is testing our PCM1820 in their real system.
Now they meet a HPF cutoff frequency issue about our device.
In their real system, they need the frequency response <+-1dB for 20-40KHz.
In order to meet the frequency response up to 40K Hz, customer select Fs to 96K Hz.
From our PCM1820 datasheet, it shows our PCM1820 integrate internal HPF in our device. It shows the -3dB cutoff frequency is 0.00025*fs.
So the -3dB for 96K fs is: 96K*0.00025=24Hz. (they need 20Hz <+-1dB), that means our device can not match their design requirement.
We try to increase the input Coupling Capacitors from 4.7uF to 47uF, the HPF -3dB is about 24Hz, that means the test result match our datasheet, but the test result can not match customer design requirement.
I think that is relate to our device internal HPF.
Do u have any comments about this case? How can we guarantee frequency response <+-1dB for 20-40KHz @96K Fs？
Thanks.
G.W
