[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 (aLAP) <John@xxxxxxxxxxxx> aoXTR!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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