From: John Larkin
Subject: Re: Bypass capacitor position
Date: Sat, 26 Oct 2002 09:10:36 -0700
Organization: Posted via Supernews, http://www.supernews.com
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On Fri, 25 Oct 2002 05:18:10 GMT, "Richard Haendel"
>Everyone knows that bypass capacitors should be as close as possible to an
>ic's power and ground leads. That's easy, of course, in the case of some
>PICS (for example) when power and ground are directly opposite to each other
>and your using an ic socket that has room for a small capacitor.
>But my question is: can the capacitor be as far away as, say, .2" or .4" and
>still be effective (at about 8Mhz)? If the cap can't be equi-distance from
>both leads, should it be closer to positive or ground? Or does it really
>Note that I'm talking about pc boards with through hole devices, not
>breadboads and not smts.
Did you ever wonder why so many people have such firm, and different,
views on bypassing?
I humbly suggest that this is because they each do it their way, and
it works, so they know their way is right. The reality is that all
sorts of bypassing schemes work fine, and that it's usually grossly
overdone. I've known people who put a big ceramic, a little ceramic,
and a tantalum on every chip, and I met a pretty senior guy at an
aerospace company who uses no bypass caps at all on multilayer digital
So it's like audio: violent opinions all around but, in a blind test,
everything sounds pretty much the same.