DJ Delorie wrote: >> Traces from the pin to be decoupled (bypassed) to teh cap should be as >> short as possible and as fat as possible. Nothing wrong with making a >> small plane out of that because it provides a small additional "courtesy >> capacitance", for free, to the ground plane below. > > Comparison: http://www.delorie.com/electronics/powermeter/bypass-1.png > > The top is the "new" way, the bottom is the "old" way. >
Better. You don't really need a plane at the GND side of C33 though. C30 is 1/2" away from the pin but not much you can do. Make the supply line to pin 2 even fatter, heck, pour it all underneath the chip. > I thought about adding a rectangle of copper under U30 tied to AVdd to > act as a tiny cap, but I calculated it was only 0.2pF. Maybe I'll use > the space to add a big fat GND trace instead. > Yes, it ain't much. But free. However, I'd use the area to fatten up the digital supply from C30 to pin 2 even more. Reduces the rattle at pin 2. Can't see the schematic right now from your previous post because I managed to screw up my Ubuntu a bit when I could not coax it to go full screen in VirtualBox. Might need a re-install. Oh well, still learning. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
