What is the Best way to route signals on split plane.

Status
Not open for further replies.
T

tux

Member level 4
Joined
Sep 6, 2005
Messages
71
Helped
5
Reputation
10
Reaction score
3
Trophy points
1,288
Activity points
1,832
split power plane

Hi

I have scenario were is have to route traces crossing two split plane.
What is the best way to do it..

--thanks
tux
 

stitching caps

Place stitching capacitors that connect to the planes that are crossed and try to place them as close as possible to the traces that cross the planes. I think 0.1uF caps are acceptable.
 

power plane split

U can use vias connecting the same reference planes near the Trace where they are crossing the spilt plane
 

problem with signal crossing gap in ground plane

if you have a DGND and an AGND and you want to route a sensitive analog signal, then dont use stitching caps. if the circuit enables, route as a differential pair, where one signal is your signal, the other is the GND at the source. Then you have to measure the signal at the input, as a differential signal.

But if they are two digital power planes, then the stitching cap is the solution. Or route the signals as GND-referenced on another signal layer.
 

power plane split

I guess you have a small numbers of layers (maybe two).

This is a zero solution problem as long one plane is GND ground, the other is AGND ground and routes goes between AGND to GND (common situation is routing A2D converter analog signals or analog clock).

Mix AGND and GND planes in such a way there will be return path for the signals and will not be return path for digital noise (separe GND and AGND with a gap in analogic area and let them continous elsewhere). Use if possible some array inductances for every digital signals.

For the solution of using stiching caps (or inductors or zero ohm resistors which means the same): will create a mixture between those two planes.
 

stiching capacitors

Hi

Its a four layer board and the layer stackup is like this

1. top
2. split ground plane
3. split power plane
4. bottom

where i have to route around 20-30 signals crossing split power plane.

is there any application notes or standard guide lines available for the same.

wheather i can use cap array for stiching the same ?

--thanks
tux
 

routing over split power planes

what signals have the eproblem? digital or analog signals?
 

split power planes

HI,

If your signal crossing only the split power plane, then there won't be problem. Since you have the gorund above the split plane. That is the signal will take the immmediate return path below which the signal is routed. In your case the immediate ground path is ground.


In case if you have split ground plane, then you may follow ground traces paralley running for each traces will help you to solve your problem.

SP_harikrish
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…