[SI-LIST] Re: Power plane resonace for multi-plane issues
- From: =?big5?q?sghsu55?= <sghsu55@xxxxxxxxxxxx>
- To: John@xxxxxxxxxxxx, si-list@xxxxxxxxxxxxx
- Date: Wed, 2 Jun 2004 17:24:15 +0800 (CST)
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 (�L�·�) <John@xxxxxxxxxxxx> ���T���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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