Re: gEDA-user: terminators

[Steven Michalske <smichalske@xxxxxxxxx>]

On Apr 21, 2009, at 11:04 PM, Bert Timmerman wrote:

> Hi DJ,
>
> On Tue, 2009-04-21 at 23:35 -0400, DJ Delorie wrote:
>> Update...
>>
>> I added serpentines to the short traces, and re-routed the long  
>> traces
>> to go under the sdram chip instead of around it, and got the
>> following...  Only 381 mils difference between the shortest and
>> longest.  http://www.delorie.com/electronics/sdram/
>>
> <snip>
>
> Your board looks nice, as always.
>
> I was told to avoid 90 degree angles in traces, it was something about
> impedance or EMI, IIRC.
>
> You do not expect some EMI problems or high impedance from the 90  
> degree
> cornered angles ?
>

Em fields are concentrated at sharp points,  thats the main reason for  
not having 90 degree bends.
In this case it is the sharp inside edge.

I forget if the close parallel traces affect it but they might have an  
effect on impedance at much higher frequencies

I wonder if by mentioning the serpentines would look cool as arcs, we  
would get a plugin that makes arc serpentines out of a line. ;-)

>> And yes, I added a command to show the length of all nets.
>> Report(AllNetLengths).  I also used a script to remove the logic
>> analyzer traces from the above report, and pull out the nets I  
>> wanted.
>>
>>
>
> Report(SelectedNetLengths)  comes to mind (may be, or may be not
> implemented yet).
>
> Kind regrds,
>
> Bert Timmerman.
>
>
>
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