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Altera_Forum
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9 years ago

CycloneIV VCCD_PLL Decoupling

Hi, what is the appropriate ground connection for the VCCD_PLL pins? None of these have GND pins nearby in the E22 package, but the name suggests that this is a digital pin, so it is refer...
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Altera_Forum
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9 years ago

Simon -

I recommend not using the approach of running traces to the IC pins from the bypass caps (your first image). Dropping vias from the caps directly to the power and ground planes is the best option. Inductance is the enemy here and the inductance is higher with the trace-to-pin approach. Read just about any book written in the last 25 years on high-speed digital design, signal integrity, etc, for an explanation. The only exception would be if you don't have solid power planes to connect to, but without solid planes you would have bigger problems to worry about than how to connect your bypass caps.

Bob