[SI-LIST] 回复： Re: 14 Layer Stackup
- From: 彬 龙 <alonger2002@xxxxxxxxxxxx>
- To: xileil@xxxxxxxxxxx, jain.nitin@xxxxxxxxx, leeritchey@xxxxxxxxxxxxx
- Date: Tue, 20 Jun 2006 10:31:07 +0800 (CST)
Hello:
I quite agree with what Celine said.Yes, about Jain's top It is not very good
solution for VD1 if VD1 is the main power plane.If you do not need so much
signal plane,I highly suggest the following stackup .
>Top 1
>Plane 2 GND
>Signal 3
>Plane 4 Power1
>Plane 5 GND
>Signal 6
>Plane 7 Power2
>Plane 8 GND
>Signal 9
>Plane 10 Power3
>Plane 11 GND
>Signal 12
>Plane 13 Power4
>Bottom 14
If three power plane is enough, You can change a power plane to the GND plane,
for example change layer 4 to GND plane, then you can route all the clock and
key signals in layer 3( because of Both side GND reference at the layer), In
addition:1> make all the singals plane is more closer to the GND plane than
Power plane to make sure the signal reference plane is GND,
2> make the distance between Power Plane and GND plane as short as
possible,may be 4mil is OK.
In my opinion,It is best to make all siganls refer the GND plane,If the high
speed signals refer the Power Plane,the image current will go through the
capaictance between the signal plane and GND and form a loop, cause EMI
problem,as Celine has said in the previous email.if this case is unavoidable
then we need to reduce the area of the loop,maybe we can short the routing at
the capaictance Pins and make the Power plane beneath a Gnd.and so on.....
And if 8 signal layers is needed, I think the following stackup is OK
> > Top 1 top
> > Signal 2 Signal
> > Plane 3 Plane Gnd
> > Signal 4 Plane Vdd1
> > Plane 5 Signal
> > Plane 6 Signal
> > Signal 7 Plane Gnd
> > Signal 8 Plane Vdd2
> > Plane 9 Signal
> > Plane 10 Signal
> > Signal 11 Plane Vdd3
> > Plane 12 Plane Gnd
> > Signal 13 Signal
> > Bottom 14 Bottom
But with this stackup, we need to arrange the distance between layers properly
1>,make the distance of two closer singal plane as great as possible.
2>,make the distance of two closer power plane(GND & Power) as short as
possible,the same as the signal Plane and Power Plane
3>,As less routing as possible at Top and Botton layer
And keep in mind to make the impedance of all layers are equal
I hopy it helps you
Kun.
Xilei Liu <xileil@xxxxxxxxxxx> дµÀ£º
Hi Jain,
What's the signal operation frequency and which Vdd is the main power plane
(the one with greatest power supply)? I think it is better not to have Vdd1
in layer 3 sanwiched by two signal planes. The main power plane should be
beneath a Gnd, and the high-speed signal plane should be close to Gnd,
otherwise the image current will go through the capaictance between the
signal plane and GND, which will form a loop and cause EMI problem.
Celine
>From:
>Reply-To: jain.nitin@xxxxxxxxx
>To:
>CC:
>Subject: [SI-LIST] Re: 14 Layer Stackup
>Date: Mon, 19 Jun 2006 20:34:26 +0530
>
>
>Hello Lee,
>
>Thanks for the information. I had thought about the stackup you just
>suggested. I have a issue with this stackup. I have lot of high speed
>differential nets to be routed and if I use the stackup you suggested
>I'll have to route in board side coupled fashion which is not easy (in
>terms of cost, reliability etc). What do you think if I have some kind
>of following arrangement:
>Top 1
>Signal 2
>Plane 3 Vdd1
>Signal 4
>Plane 5 Gnd
>Plane 6 Vdd2
>Signal 7
>Signal 8
>Plane 9 Gnd
>Plane 10 Vdd3
>Signal 11
>Plane 12 Gnd
>Signal 13
>Bottom 14
>
>I think you might not very comfortable with Vdd1 in layer 3. What issues
>I can face if I go with above stackup.
>
>With regards,
>Nitin
>=0D
>-----Original Message-----
>From: Lee Ritchey [mailto:leeritchey@xxxxxxxxxxxxx]=0D
>Sent: Monday, June 19, 2006 8:14 PM
>To: Nitin Jain (WT01 - Broadband Networks); si-list@xxxxxxxxxxxxx
>Subject: RE: [SI-LIST] 14 Layer Stackup
>
>Jain,
>
>I'd suggest you change the stackup as I have shown below. Then, I'd
>make layer assignments as shown.
>
>
> > [Original Message]
> > From:
> > To:
> > Date: 6/19/2006 10:01:00 AM
> > Subject: [SI-LIST] 14 Layer Stackup
> >
> >
> > Hello,
> >
> > We are planning to use 14 layer stackup for our design. In our stackup
>
> > we have total 6 planes and we are planning to use 3 planes as power=0D
> > planes and hence we are left with 3 gnd planes. Now I want to know is=0D
> > there any defined strategy to assign planes as pwr or gnd. In other=0D
> > words which plane should be assigned as pwr and which should be=0D
> > assigned as gnd.=3D0D =3D0D The 14 layer stackup looks like this:
> >
> > Top 1 top
> > Signal 2 Signal
> > Plane 3 Plane Gnd
> > Signal 4 Plane Vdd1
> > Plane 5 Signal
> > Plane 6 Signal
> > Signal 7 Plane Gnd
> > Signal 8 Plane Vdd2
> > Plane 9 Signal
> > Plane 10 Signal
> > Signal 11 Plane Vdd3
> > Plane 12 Plane Gnd
> > Signal 13 Signal
> > Bottom 14 Bottom
> >
> > With regards,
> > Nitin
> >
> >
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