[ibis-macro] Re: Updates to BIRD 145

Hi Feras,

I have a couple of questions about this BIRD.

Using the following IBIS keywords and values as an example:
---------------------------------------------------------------------------------------------------
[Voltage Range]             1.5000V             1.4250V             1.5750V
[Pullup Reference]          1.5000V             1.4250V             1.5750V
[Temperature Range]        50.0               120.0               -40.0
[Pulldown]
|       Voltage            I(typ)             I(min)             I(max)
     -1.50000000E+0    -16.49945000E-3    -12.54515100E-3    -17.87071600E-3
     -1.42500000E+0    -17.26897000E-3    -13.59391400E-3    -18.38734400E-3
......
---------------------------------------------------------------------------------------------------

Suppose the user has selected the typical case for simulation, corresponding to 
voltage = 1.5000V, temperature = 50.0.

For case a) in your email: if an external circuit is inserted between the 
external power supply and A_puref, the actual voltage of A_puref can deviate 
from 1.5V. As a result the typical V-I curve (which was obtained for 
A_puref=1.5000V)  will no longer apply to this simulation. What is the proposed 
approach for this situation?

For case b) in your email: This BIRD proposes no changes to how the power 
supplies are connected to the model when the power nodes are floating. However, 
I'd like to enter this question here anyway for the record: what happens if a 
user connected the A_puref to a voltage other than 1.5000V (such as 1.52385V) 
and selected  the typical V-I curve ? Further, what if the user composes a 
power circuit outside of IBIS and connects it to the A_puref pins in the EDA 
tool?

This BIRD presents a format to include power distribution circuits in IBIS. At 
the same time it should also clearly articulate how this new structure and data 
should be simulated when power supply voltages deviate from those prescribed 
values in native IBIS V-I curves.

Thanks,
James Zhou
QLogic Corp.




From: ibis-macro-bounce@xxxxxxxxxxxxx [mailto:ibis-macro-bounce@xxxxxxxxxxxxx] 
On Behalf Of Feras Al-Hawari
Sent: Monday, March 05, 2012 1:48 PM
To: 'IBIS-ATM'
Subject: [ibis-macro] Updates to BIRD 145

I have updated BIRD 145 (will be uploaded soon) to explain whose responsible 
for delivering power to the reserved voltage reference nodes in examples 1 & 2 
. The new changes are preceded by **. The bulk of the changes are as shown 
below:

|*             The pre-defined voltage reference ports (i.e., A_pcref, A_puref,
|*             A_pdref, A_gcref) of any [Model] that is called in the circuit
|*             can be either: a) manually interconnected by the model developer 
to the
|*             ports of an [External Circuit] by connecting them to the same 
node
|**            declared by the [Node Declarations] keyword as shown in example 
1 below
|**            (i.e., in this case the model developer needs to guarantee that 
the
|**            [External Circuit] contains the appropriate circuitry to deliver 
the
|**            required power to each of the voltage reference ports), or b) 
automatically
|**            interconnected "as usual" by the EDA tool to the corresponding 
voltage
|**            sources when those ports are left floating as shown in example 2
|**            below (i.e., in this case the EDA tool should connect the 
reserved
|**            voltage reference ports to DC voltage sources with voltage values
|**            equal to the corresponding reference voltage values in the 
[Model]).

Feras



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