FreeLists / si-list / [SI-LIST] Re: Power plane resonace for multi-plane issues

[=?big5?b?Sm9obiBMaW4gKKpMtMK31yk=?= <John@xxxxxxxxxxxx>]

My special thanks to Sogo, who was my instructor in using SpeedXP =
several years ago.

He pointed out that I used 4 resistors (0.1 ohms) to short VRM to form a =
current loop in my simulation. For measurement, I used 4 wires to short =
VRM to mimic the 0.1 ohms. It was wrong. I should also use wires to =
short VRM in my simulation to  match the simulation with measurement.

He is right. Now the correlation looks much better..

I appreciate his helps... Thanks again

John

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of John Lin =
(=AAL=B4=C2=B7=D7)
Sent: Wednesday, June 02, 2004 2:15 PM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Power plane resonace for multi-plane issues


Dear all SI gurus,
one question regarding Power plane resonance.=20
Currently, I use SpeedXP from Sigrity for simulating power plane =
resonance. =20
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   =20
          ....
           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. =20
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          =20


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