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Altera_Forum
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16 years ago

Cyclone III, huge cap at VCCD_PLL

Hi All! Altera document "Cyclone® III Device Family Pin Connection Guidelines PCG-01003-1.0" says that 470 uF capacitor must be used at digital power of PLL (besides a lot of ceramic capacitor...
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Altera_Forum
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16 years ago

I think that the reason is real. PDN consists of several ceramic capacitors and its own resonanses are far from inductive component of bead impedance, so LC oscillation tank[s] takes place in any case. What do you propose to prevent negative influence of the parasitic resonances? IMHO, the using of large bulk capacitor is good enough solution.