Hi, I am using FMC150 with the ML605 (Virtex-6) and having some issues regarding the AD converter. In the reference design provited by avnet for a DA/AD loop, it was implemented an auto-calibration stage before the AD starts working with any data conversion. I have tested the AD with sampling frequencies above 80 MHz and got no problem at all, but when it comes to 40, 60 or 70 MHz, for example, it cannot be auto-calibrated and, thus, I get degraded signals. I'm using external clock source and enabled Low Speed Mode too. Any support on what I could be missing will be appreciated. Thank you. Magno.