In the link attached there is a note saying that there is a bug in the ADC IP that makes the TSD error outside the tolerance band and that it would be fixed with later versions of Quartus. However, I saw this problem on Quartus 16.1 (which is a later version than what this post was referencing) and after downloading and testing Quartus 18.1. Either the software bug hasn't been fixed or this is actually a hardware issue. Can I get some insight here? Thanks.