[SI-LIST] Re: 50 ohm and 130 ohm on the same board
- From: "Salkow, Steven" <steven.salkow@xxxxxxxx>
- To: prasadsa@xxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Wed, 02 Jun 2004 10:59:03 -0700
S A Prasad:
You could use a low dielectric material on exterior surfaces such as =
Polyimide (3.1~3.3) this will help. However, 50 ohm trace widths would =
be around 1.27 mm (0.050") which is a size good for RF circuits for 0805 =
components. Alternatively, Void out the top two layers under the 130 ohm =
layers so the height above the plane is taller. The limititing factor on =
this is the overall board thickness.
Hope that was useful
Steve Salkow=20
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-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of saprasad
Sent: Wednesday, June 02, 2004 8:09 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: 50 ohm and 130 ohm on the same board
Hello All,
I have a board with 2 sets of signal, the first set of nets need to be =
at 50ohm characteristic impedance and the other at 130ohm (single =
ended). This is not practically possible due to manufacturing =
constrains.
Can you suggest me some technique so i can archive this on the board.
Board details are as fallows:
No. of Layers: 6
Stackup: top, ground, signal, signal, power, bottom
Board thickness is 1.6mm
Regards,
S A Prasad
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----- Original Message -----
From: "sghsu55" <sghsu55@xxxxxxxxxxxx>
To: <John@xxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
Sent: Wednesday, June 02, 2004 2:54 PM
Subject: [SI-LIST] Re: Power plane resonace for multi-plane issues
>
> John,
>
> We have ever conducted lots of simulation and
> measurement for the
> similiar PDS structure as you described. In our
> experiences, SpeedXP
> can got quite accurate results with VNA measurement. Especially, the
> prediction of resonance frequency of PDS plane pair.
> The results of
> SpeedXP were slightly greater than measured as well
> may come from the
> fringing effect in the edge of plane. I don't have
> sufficient
> information to understand your case and simulation
> setting. However,
> in my opinion, I don't think that the overlap between
> VCCP and VCC3_3
> is a good design.
>
> Best regards,
>
> Sogo Hsu Ph. D.
>
> Foxconn
>
> --- John Lin (aL=A1=A6A=A1P=A1=D1) <John@xxxxxxxxxxxx> =
ao=A2XTR=A1=B1!G>
> Dear all SI gurus,
> > one question regarding Power plane resonance.
> > Currently, I use SpeedXP from Sigrity for simulating
> > power plane resonance.
> > The set up is that
> > TOP layer : VCCP
> > ----- on top layer,
> > 2nd layer : GND, VCC3_3 --
> > partially overlap both plane on the second layer
> > 3rd layer : GND
> > ....
> > BOT layer: VCCP --
> > on bottom layer
> >
> > I inject a current pulse into VCCP at a node on the
> > top layer. With Fourier transfer for voltage and
> > current, and got a plot of plane impedance. My VNA
> > measurement shows a resonance at 50 Mhz, but the
> > simulation show 100Mhz.
> > I think the mismatch may be among , VCCP,VCC3_3, and
> > GND plane . Shall I let VCC3_3 plane float or tie
> > it to somewhere?
> >
> > I know Cadence's PI tool need to specified each
> > overlapping plane pairs with correct voltage
> > difference for multi-plane issues.
> >
> > I don't know how to take care current injection
> > issues on Sigrity SpeedXP for multi-planes.
> >
> > Does somebody please kindly shed some light on it.
> >
> > Thanks,
> > John
> >
>
>
>
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