You can get AmiPro hereTones due to static signals are described in every introductory text on delta-sigma converters. DC offsets caused significant tones in the earliest designs (low-order, single-bit). Higher-order loops, dither (noise decorrelation), and multibit designs pretty much killed them many years ago. But it seems like the DEM schemes used to improve the multibit converters has brought this old problem back. Ironically back in the mid-1990's I was designing a DAC and considered DEM. I scrapped it mainly due to power and voltage headroom issues, but did see the modulation described in the slides when I used a simple shifter. I had totally forgotten about that. I went to a PRNS (pseudo-random noise source) and that squelched the tones.
I have some old notes for a college class I gave on DS converters but when I tried to resurrect the notes a couple of years ago I failed. It was in AmiPro; MS Office had but no longer has a converter, and a comercial converter got the text but not the figures -- and it was pretty much all figures! Blah. It had a few slides on tones with pretty pictures. Including Bessel functions, not one of my most favorite things... They are also used in the derivation of SFDR for an ideal converter.
https://winworldpc.com/product/amipro/3x