[SI-LIST] Re: IBIS Confusion over Component/Package/Pin vs Define Package Model
- From: "Beal, Weston" <Weston_Beal@xxxxxxxxxx>
- To: Russell Dill <Russ.Dill@xxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Tue, 9 Aug 2011 19:49:14 +0000
The first problem is that the resistance values are negative. I think that
means that the package pin is generating power. If that's real, we'll all buy
some. The bad resistance values bring the whole model into doubt. My choice
would be to remove that package model, move forward with the lumped RLC per
pin, and in parallel ask the IC vendor to correct their model so I can run a
final verification with the best possible model.
Regards,
Weston
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Russell Dill
Sent: Tuesday, August 09, 2011 1:43 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] IBIS Confusion over Component/Package/Pin vs Define Package
Model
I'm looking at the Component/Package/Pin RLC values of an IBIS component
(Micron 2Gb DDR2 SDRAM) and the Package Model RLC data. I realise they won't be
identical since they are measuring different things, but even in the case of
banded matrix components with 0 bandwidth (resistance matrix) they are way off.
For example, From the Component/Package/Pin section:
[Pin] signal_name model_name R_pin L_pin C_pin
[...]
L1 BA2 INPUT 293.00m 2.27nH 0.40pF
L2 BA0 INPUT 225.78m 1.80nH 0.31pF
L3 BA1 INPUT 164.66m 1.31nH 0.24pF
And from the define package model section:
[Model Data]
[Inductance Matrix] Sparse_Matrix
[...]
[Row] L1
L1 2.2E-09
L2 3.7E-10
[...]
[Row] L2
L2 1.69E-09
L3 6E-10
[...]
[Row] L3
L3 1.2E-09
L7 -6.59E-12
The inductance matrix is reasonable close...
[Capacitance Matrix] Sparse_Matrix
[...]
[Row] L1
L1 4.8E-13
L2 -3.47E-14
[...]
[Row] L2
L2 3.84E-13
L3 -1.05E-13
[...]
[Row] L3
L3 2.94E-13
L7 -4.26E-15
The capacitance matrix a little further off.
[Resistance Matrix] Banded_Matrix
[Bandwidth] 0
[...]
[Row] L1
-0.001546917
|
[Row] L2
-0.000994774
|
[Row] L3
-0.001111145
But the resistance matrix is off by a few orders of magnitude. I must be
missing something really basic. What am I not understanding here?
Or is this model just out of whack?
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