[ibis-macro] AMI and direction, for single-ended buffers

  • From: "Mirmak, Michael" <michael.mirmak@xxxxxxxxx>
  • To: "IBIS-ATM (ibis-macro@xxxxxxxxxxxxx)" <ibis-macro@xxxxxxxxxxxxx>
  • Date: Sat, 8 Feb 2014 05:53:25 +0000

Imagine that you have a set of AMI files and an IBIS file for a device 
containing exactly one transmitter and one receiver.  However due to file 
corruption and some missing documentation, the [Algorithmic Keyword] pairs are 
missing the DLL and AMI parameter file names - you don't know which files are 
associated with the transmitter and which are for the receiver.



Would you have any way to find out, other than experimenting with the files in 
an EDA tool?



Reading the specification, the text clearly assumes that AMI files have a 
"direction" - either input or output, based on the frequent references to TX 
and RX.  Further, this would imply that Input and Output (and their variants) 
are the only expected Model_types.



Yet the specification only prohibits the use of Model_types Series, 
Series_Switch, and Terminator with AMI models.  I/O and its variants are not 
prohibited.



So what if one wants to use AMI techniques for single-ended models, which is 
explicitly allowed by the specification?  Single-ended interfaces today are 
more likely to be bi-directional.



If you actually associated Model_type I/O with AMI information, there's no 
obvious way to identify to the tool (or the user) outside of a Model Specific 
parameter or tool-specific setting the current direction of the model, or 
whether the AMI file is capable of bi-directional operation at all.  The flows 
assume unidirectional operation or an unambiguous identification of the TX and 
RX in any given situation.



Do we need to prohibit I/O Model_types with [Algorithmic Model]?  Or, probably 
more usefully, do we need to define a Reserved Parameter for AMI that 
identifies directionality both for the AMI file as a whole, as well as its 
current state if it is an I/O?



-          MM

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