Cyclone III, huge cap at VCCD_PLL

I don't want to put you of using a 470 uF capacitor. As jacobjones, I just doubt it's necessity and reported, that I didn't yet use a similar value. But I'll check some common supply filter dimensioning if they actually show a low frequency resonance as assumed in the AN. For some reason, I don't expect this high low pass (or "antiresonance") Q. But I may me wrong.

As another point, that hasn't been addressed yet. It's no obvious in my opinion, that VCCD has a high susceptibility for interferences at all. It's pretty clear for VCCA, although pleasantly reduced with newer devices, that have an internal PLL voltage regulator. In practice, I only experienced PLL supply issues with 1.2V VCCA of older devices.