At 03:40 AM 4/13/2004, [EMAIL PROTECTED] wrote:
I think if Altium would decide that they have automated the bypassing process, it would be the last straw for many people who will realize that Altium has completely lost it.

In my opinion, this is a narrow view. Yes, bypassing can be a complex issue, and, yes, I noted problems with the bypassing scheme described in the post to which Mr. Wasti was responding; however, that does not mean that there are no tools which could be provided to assist the designer. (Whether these tools should take priority over more fundamental issues is another question.)

First of all, it could be possible to create a layout directive attached to a component or component pin that specifies a certain distance from another component or component pin. There might be options as to how "distance" is defined.

Secondly, it might be possible to assign to a component class a certain number of bypass capacitors, checked and possibly autoplaced to within a certain distance of components within that class. Naturally, there would be another component class for the caps.

And more, much more, could be done. Signal-integrity type analysis could be done on power nets, perhaps. Sometimes it is necessary to do a design without benefit of power planes for cost reasons. It's expensive to go to copper only to find out that power distribution is too noisy, that the floor is lifting whenever some outputs switch.

None of this would pretend to make the skill of the designer unnecessary. But it could speed up his or her work at least a little.

(As to a generic bypassing method, mine has been to connect all power pads and bypass capacitor pads directly to a power/ground plane with as short a track as possible. If I could, I'd put the vias right in the pads -- that can work with blind vias, I've thought, but have never tested, and might work under other circumstances but is not a generic solution because of soldering quality issues. The exact placement of capacitors, here, is not usually critical; the primary bypass capacity is coming from interplane capacitance and, yes, the stackup is controlled to maximize interplane capacitance.)

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