[IBIS-Users] IBIS [Add Submodel] workaround

  Hi,

I use EDA tool called Altium. It uses old version of ibis so every time
I want to do analysis I need to modify IBIS file for Altium to accept it.

I know for a fact that Altium does not support [series_switch], [Add
Submodel] and [Model Selector]. I do not need to workaround
[series_switch], and i have managed to work around [Model Selector].

Now the last thing I need to do is to work around [Add Submodel] keyword.

I'm simulating DDR3 memory modules, and I want to use their On Die
Terminations (ODT). Pin model looks like this:

    [Model] DQ34_ODT20_1066
    Model_type I/O
    .
    . some normal stuff from
    . model definition here
    .
    [Add Submodel]
    | Submodel Name Mode
    20Ohm_ODT_1066 Non-Driving
    |
    [Temperature Range] 85.00 110.00 0.00
    [Voltage Range] 1.500V 1.425V 1.575V
    [Pullup Reference] 1.500V 1.425V 1.575V
    [Pulldown]
    .
    . Pulldown table here
    .
    [Pullup]
    .
    . Pullup table here
    .
    [GND Clamp]
    .
    . GND Clamp table here
    .
    [POWER Clamp]
    .
    . POWER Clamp table here
    .

After this are other model definitions, and my submodel is defined after
them:

    .
    .
    [Submodel] 20Ohm_ODT_1066
    Submodel_type Dynamic_clamp
    |
    |***************************************************************************
    |
    [GND Clamp]
    |
    .
    . Submodel's GND Clamp table here
    .
    [POWER Clamp]
    |
    .
    . Submodel's POWER Clamp table here
    .

Since Altium does not support [Add Submodel], I can get correct results
for this pin only if I set it to output (driving). If it is set to Input
(Non-driving) a submodel should be used, and I will get wrong results.

Now, I want to modify this IBIS file by "implementing" data from
[Submodel] into [Model]. This way I would get correct results when doing
analysis with this pin set as input. I know that by doing that I will
not get correct results with this pin set as output, but that is OK. I
will then combine two IBIS files based on the analysis that I'm doing.

Do I have to simply replace [GND Clamp] and [POWER Clamp] tables from
the [Model] with the ones from the [Submodel], or do I have to use some
arithmetic functions in order to combine the two (or something third).

I hope I was clear, since I find this very hard to explain :-)

Regards
Petar Perisin

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