[SI-LIST] Re: Effect of Split Planes on Single Stripline Signals

  • From: Istvan Novak <istvan.novak@xxxxxxx>
  • To: Walter <waltinaustin@xxxxxxxxx>
  • Date: Sat, 12 Jun 2010 11:36:53 -0400


There are a few more details to take into consideration:
- what is the stackup beyond the split plane?  If you have a solid 
ground plane close behind the split plane, it helps.  On the other hand, 
if you have further (possibly split) power planes beyond the split-plane 
layer, it will make things worse.  You will find graphs illustrating the 
former in Jason's paper referenced below.
- what do you carry on the (split) planes?  Though this is not 
specifically a split-plane problem, even when we offset the stripline 
away from a plane layer, we need to consider the magnitude of noise 
expected on the plane.  If supply rails related to your signaling, it is 
safer as opposed to say a high-voltage (12V or 48V) input rail.  In the 
offset stripline stack a noisy 12V plane should be much further away 
from the trace layer


Istvan Novak

jason.miller@xxxxxxxxxx wrote:
> You may find this paper helpful:
> http://www.electrical-integrity.com/Paper_download_files/DC09_10-WA3--Jason_Miller.pdf
> Jason Miller
> On Jun 9, 2010, at 5:00 PM, Walter <waltinaustin@xxxxxxxxx> wrote:
>> I have an application were I am contemplating routing signals across  
>> splits in a plane. Everyone know that this is a big no no for high  
>> speed signals. But in this case, it's a asymmetric single stripline.  
>> The traces are 12 mils from a split plane and 3mils from a solid  
>> plane. Can I expect a measurable effect on my DDR3 1600 signals? I  
>> would like to simulate this with a 3d solver but I don't have access  
>> to one.
>> Regards,
>> Walter Haskell
>> Polycom. Inc.

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