[SI-LIST] Re: Return current and stack up

  • From: "Istvan Nagy" <buenos@xxxxxxxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>, <jhasson@xxxxxxxxxxxxxxxxxxx>
  • Date: Thu, 11 Jun 2009 18:23:08 +0100

hi

its hard to say this way (without adequate caps/ stitching vias), but i 
think you should make shure that you have VCC1-GND decoupling capacitors 
close to both the driving IC and the signal-via-transition 
(layer1-to-layer-5).
Then it would go this way: from IC gnd-pin, to gnd plane, through the 
vdd1-gnd decap to vdd1 plane, through the vdd1 plane following the signal, 
through the vdd-via of the vdd1-gnd decap at the signalvia, through the 
decap itself, through the gnd-via of the decap, to both gnd planes, then 
following the signal in both gnd planes.
vdd2-gnd decap is not even involved, i think. Or route primarily on layer 5 
or 4 and dont change layer.

regards,
Istvan Nagy
Concurrent Tech. plc, UK



----- Original Message ----- 
From: <jhasson@xxxxxxxxxxxxxxxxxxx>
To: <si-list@xxxxxxxxxxxxx>
Sent: Thursday, June 11, 2009 4:31 PM
Subject: [SI-LIST] Return current and stack up


> Hi,
> Asumming I have the following 8 layer stack up :
> Layer 1 - - - - - - - Sig
> Layer 2 - - - - - - - VCC1,VCC3
> Layer 3 - - - - - - - GND
> Layer 4 - - - - - - - Sig H
> Layer 5 - - - - - - - Sig V
> Layer 6 - - - - - - - GND
> Layer 7 - - - - - - - VCC2,VCC4
> Layer 8 - - - - - - - Sig
>
> What would be the return path of a signal going from layer 1 (for 2 inches
> running above VCC1 for instance) to layer 5 (for 4 inches) driven by a
> component powered by VCC2 if the component is set up above layer 1 and
> driving high ? Would it be going through decoupling capacitors of VCC2 to
> decoupling capacitors of VCC1 to then get to the layer 6 reference plane ?
>
> Best regards,
>
> JF Hasson
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
> List technical documents are available at:
>                http://www.si-list.net
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
>  http://www.qsl.net/wb6tpu
>
>
> 

------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List technical documents are available at:
                http://www.si-list.net

List archives are viewable at:     
                //www.freelists.org/archives/si-list
or at our remote archives:
                http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
                http://www.qsl.net/wb6tpu
  

Other related posts: