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BIRD ID#:        117
ISSUE TITLE:     Parameterize A_to_D and D_to_A Converters
REQUESTER:       Arpad Muranyi, Mentor Graphics
DATE SUBMITTED:  September 29, 2010
DATE REVISED:    
DATE ACCEPTED BY IBIS OPEN FORUM:  

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STATEMENT OF THE ISSUE:

[External Model]s and [External Circuit]s with analog ports communicate 
through A_to_D and/or D_to_A converters with the purely digital signals of
the EDA tool.  The current specification only allows hard-coded values for
arguments to these converters in the IBIS file.  For various reasons it would 
be desirable to parameterize the arguments of these converters so that 
parametric sweeps could be performed by the user of the EDA tool.

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STATEMENT OF THE RESOLVED SPECIFICATIONS:

A new subparameter called "Converter_Parameters" shall be added to the
[External Model] and [External Circuit] keywords which shall list any
arbitrary parameter names that are used for the arguments of the A_to_D
and/or D_to_A converters.  These parameters are required to have a value
assignment to initialize the parameter with a default value.


On pg. 107 and pg. 126 add the following lines after the "Parameters:" section:

|               Converter_Parameters:
|
|               Defines the names of parameters which are used for the A_to_D
|               and/or D_to_A converters of the [Extrenal Model].  Only one
|               parameter definition is allowed per line, and the parameter
|               must be initialized with a default value assignment.  The
|               EDA tool may assign different values to the parameters via
|               interactive dialogs or other means.


On pg. 108 and pg. 127 insert after this paragraph:

|               The vlow and vhigh entries accept analog voltage values which
|               must correspond to the digital off and on states, where the
|               vhigh value must be greater than the vlow value.  For example,
|               a 3.3 V ground-referenced buffer would list vlow as 0 V and
|               vhigh as 3.3 V.  The trise and tfall entries are times, must
|               be positive and define input ramp rise and fall times between
|               0 and 100 percent.

the following lines:

|
|*              Any or all of these entries may be defined by an arbitrary
|*              parameter name, which must be declared in the
|*              "Converter_Parameters" section of the same [External Model]
|*              keyword with a default value assignment.


On pg. 110 and pg. 128 insert after this paragraph:

|               The vlow and vhigh entries list the low and high analog
|               threshold voltage values.  The reported digital state on
|               D_receive will be '0' if the measured voltage is lower than
|               the vlow value, '1' if above the vhigh value, and 'X'
|               otherwise.

the following lines:

|
|*              Any or all of these entries may be defined by an arbitrary
|*              parameter name, which must be declared in the
|*              "Converter_Parameters" section of the same [External Model]
|*              keyword with a default value assignment.


In the example section(s) give some examples for how this would work:

| List of converter parameters
Converter_Parameters  MyVlow  = 0.0
Converter_Parameters  MyHigh1 = 3.3
Converter_Parameters  MyHigh2 = 2.0
Converter_Parameters  MyTfall = 0.5n
Converter_Parameters  MyTrise = 0.3n
|
...
...
|
| D_to_A d_port   port1      port2    vlow     vhigh     trise    tfall    corner_name 
D_to_A   D_drive  my_drive   my_ref   MyVlow   MyVhigh1  MyTfall  MyTrise  Typ
D_to_A   D_enable my_enable  A_gcref  0.0      3.3       0.5n     0.3n     Typ
|
| A_to_D d_port     port1       port2   vlow    vhigh     corner_name 
A_to_D   D_receive  my_receive  my_ref  MyVlow  MyVhigh2  Typ 


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ANALYSIS PATH/DATA THAT LED TO SPECIFICATION


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ANY OTHER BACKGROUND INFORMATION:


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