Hi Tim,

I’m glad that my email helped explain some things.

Unfortunately I cannot help with your second question because it appears to be a problem with the specific simula= tor that you are using. =A0I recommend that you contact your simulator’s customer support directly – they should be able to help you out.=A0 A= nd while talking to them, be sure to ask about the difference between ideal gr= ound and GND…=A0 You need to know.

Good luck!
Sam

From: Ibis Mod= el [mailto:ibis_model@yahoo.com]
Sent: Sunday, October 14, 20= 07 9:26 AM
To: samchitwood@sigrity.com; Server EDA
Subject: RE: [IBIS-Users] Pa= ckage Modeling in IBIS -Matrix format

Hi Sam

Thank you for your reply. It gave me a clearer picture n= ow.

I have another concern on a previous question that I had posted, which is regarding calling a .pkg file, by adding in the [Define Package Model] section into the original IBIS file to be called by the simulator. Below is the question that I posted before, I hope you or someone else have an answer to it. Thanks.

I am facing some of the problem regarding the package fi= le. I have downloaded an IBIS file together with the package model file (in .pkg format). I have a problem in adding my desired .pkg file into my current IB= IS file when I perform my simulation. Below is the situation:

I have an IBIS file with below [Component] section. Now I would like to add in a package file with the extension .pkg (which I = also place in the same folder with the IBIS file)

[Component]&n= bsp;     abc
[Manufacturer]=     studio.Inc.
[Package]
|variable        typ            =    min            =       max
R_pkg          161.54m           &n= bsp; 5.44m           &nbs= p; 459.46m
L_pkg            2.40nH            0.43nH           &nb= sp;   5.35nH
C_pkg            1.48pF            0.75pF           &nb= sp;   2.84pF
|
[Pin]&n= bsp;    signal_name          model_name           R_pin     L_pin     C_pin
1           HSTL            = ;            HSTL
2           SSTL            = ;         SSTL

However, I read somewhere in the IBIS Spec and I had tried calling t= he .pkg file by placing in the same folder as my IBIS file but to no avail. I = have some errors as such:

1. I added in the [Package Model] keyword and define the package model name as QS-SMT-cer-8-pin-pkgs

2. Then I copied the .pkg file content and paste it under the [Component] section - [Define Pac= kage Model]. But I have errors doing this as the pin numbers in the .pkg files are different from the pin number in my original IBIS file ([Pin] name g= oes 1, 2, 3 ... ) I follow the guideline of defining the package model but I could= not find a way of calling the .pkg file from my original IBIS file when I perfo= rm my simulation.

How do I used an IBIS file and include the package model which is in another separate .pkg file when I perform my simulation? Which is the best way to a= void having errors in the IBIS file so that I can load my IC modeling in the simulator tools (with errors in the IBIS file, im not able to proceed)
Will the original Lumped RLC value interfere the result after I added in the .pkg package model?

Appreciate if someone can answer my question above with = the correct step of calling a separate .pkg package file with my IBIS file in t= he simulator tool. Thanks.

Timmy

Sam Chitwood <<= st1:PersonName w:st=3D"on">samchitwood@sigrity.com> wro= te:

Hi Tim,

Sorry for my late reply. I just= now had a chance to look at the file you provided.

Every IBIS package model has a unique combination of benefits and limitations. Lynne mentioned one of the drawbacks, which is unfortunately common to many of the IBIS package models. Because of this assumption, an IBIS model should only have one logical “pin” for power and one for ground. Multiple RLCs= for a single net are dangerous.

The major benefit of this model is th= at coupling can be defined between pwr/sig/gnd. Because of this feature, the coupled RLC matrix format is the best official IBIS pack= age model format for PCB designers wanting to perform system-level SSO analysis. (I emphasize official because many package designers common= ly use other types of package models.)

However, the model has to be correctly generated and implemented in simulation. Note the attached picture; it shows one of the dangers about many IBIS models. The trouble is in th= e “ground” pin. See how it can have a capacitance term? That’s bad. You may or may not know what the PCB simulator will do with that term. The picture shows how some tools use an “ideal groundR= 21; reference node that is different from the GND node shown in the picture.&nb= sp;

Does your simulator connect “id= eal ground” and GND? You need to know this if you want to use models that contain C terms for ground nets (like the model you attached to your original email). This is also dangerous.

Thankfully, there are other ways to generate the model that do not require the use of “ideal ground”= ;. I prefer those techniques much better because then you do not have to worry= as much about what the simulator does with “ideal ground” and GND.=

In summary, be suspicious of IBIS mod= els that have either of the following:

1) Multiple pin RLCs for a single net=

[Pin]     s= ig= nal_name      model_name      R_pin    L_pin = ;   C_pin

1          VDD                POWER            1.1        1.3        1.5<= /p>

2          VDD             = ;   POWER            1.2        1.4        1.6<= /p>

2) RLC entries for =A1=B0ground=A1=B1= nets

3          VSS             = ;   GND             = ;    1.7        1.8        1.9<= /p>

Either of these can cause incorrect results in some tools.

Thanks,

Sam

From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Lynne D. Green
Sent: Monday, October 01, 20= 07 9:42 AM
To: 'Ibis Model'; 'Server ED= A'
Subject: RE: [IBIS-Users] Pa= ckage Modeling in IBIS -Matrix format

Hello, Tim,

The IBIS specification has a chapter on the PKG format.

The major limitation with PKG for= mat is that it only supports pin-to-pad (no branching).

Best regards,=

Lynne

"IBIS training when you need it, where you need it."

Dr. Lynne Green
Green Streak Programs
http://www.greenstreakprogr= ams.com
425-788-0412
lgreen22@mindspring.com

From: owner-ibis-users@eda.org [mailto:owner-ibis-users@eda.org] On Behalf Of Ibis Model
Sent: Monday, October 01, 20= 07 2:54 AM
To: Server EDA
Subject: [IBIS-Users] Package Modeling in IBIS -Matrix format

Hi,

I have come across this IBIS model with the respective package model file (in .pkg format) and it seem to me that the package information for all RLC is presented in a matrix format. Is there any avail= able document that can explain how this numbers can be useful to the user as wel= l as how they play a role in the simulation? Else, can IBIS open forum helps to explain how these values are being presented and h= ow can the simulation tools use these information to verify whether the simulator already included the package model.

I will be glad if you can point me to any document relat= ed to this matrix RLC package modeling. Appreciate your reply on this. Pl= ease find attachement the package model file.

Regards

Tim

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