PCM1753-Q1: Help needed on LPF circuit for Left and Right Channels

Hi Amrit,

The only issue I can see immediately is that you are not using VCOM to bias the signal. Because you have AC coupled the output, and not used VCOM as a bias, your output is centered at 0V, which will clip with the negative rail (GND). I would remove C40 and C45 and use VCOM to bias the output. This can be done with a relatively large resistor connected to the output, or you can refer to the datasheet (8.3.6.1) or Application Note https://www.ti.com/lit/an/sbaa322/sbaa322.pdf?ts=1648490883335&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FPCM1753-Q1 for some ideas there. 

Hi Amrit,

I can't tell you what the "exact values" are because it depends on what your goals/constraints are. The filter shown in the datasheet is a multiple feedback active low pass filter. This website has a tool to simulate ideal situations of this filter (along with many others) :http://sim.okawa-denshi.jp/en/Fkeisan.htm You could also use the same website to model the Sallen-Key architecture that you already have. 

Best regards,

Jeff