We have configured the CODEC and are passing the I2S data corresponding to a 1KHz sinewave. Sampling rate is 96KHz. We are using both internal LDOs so only a +3V3 power rail is used. We are measuring at the CODEC output pin (LOL) with nothing else on that net.
When the output is connected to a spectrum analyser we see our 1KHz tone plus very regular spectra which are only 30-40dB down and are not obvious harmonics. The spectra are roughly 632Hz apart according to the analyser.
If we feed in I2S data that is fixed i.e. generating audio with no AC content the unwanted spectra disappear.
If we feed in a 2KHz tone the spectra move further apart in frequency.
I am working through the registers at the moment but it is a big job.
Any thoughts or suggestions would be very much appreciated.
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