I'm playing around with I2S audio DACs, and noticed that across the output caps there is something small but significant non-linear going on.
With probes at either end of C62 I can see that output of a saw-tooth waveform from the DAC is perfectly flat, but after the 3.3UF cap it has a bow in it.
The scales are the same, there is very constant DC bias over the cap, and there is no load. I would have thought they would have tracked perfectly...
What is going on?
I am also pretty sure I have the wrong sort of cap - currently using some X5R 10V I had to hand. What type, hopefully in an 0805 footprint, would you recommend in the usage? I am interested to get some and see the difference.
(This is just a hobby project, for my own edification, BTW).