Bird 70.3 open issues - 2nd call

I am resending a note that I sent out before the Summit in hopes of
getting further discussion before the Open Forum call on 7/20. I have
gotten one response already in the positive. I propose we make the
changes mentioned below and vote at the following Open Forum.

Greg

Issue 1: Different inverting and non-inverting drivers

This is a legal scenario within IBIS and should be covered by BIRD 70.3. I
propose we add a new subparameter Driver_model_inv under [Test Data]. This
subparameter is only legal when Test_data_type is differential.

I think this is a pretty straight-forward solution to the issue. Any
discussion?

Issue 2: Legal combinations of Test_data_type and Test_load_type

Here are the possible combinations:

Case 1: Test_data_type = Single_ended, Test_load_type = Single_ended
Case 2: Test_data_type = Single_ended, Test_load_type = Differential
Case 3: Test_data_type = Differential, Test_load_type = Single_ended
Case 4: Test_data_type = Differential, Test_load_type = Differential

Cases 1, 2 and 4 are clear. Cases 1 and 4 are clearly allowed, and Case 2
is clearly NOT allowed. In my opinion, Case 3 should be illegal. If one
wanted to capture singled-ended waveforms for a differential driver, one
could use Case 1 and just specify the differential driver. I don't see any
differences between Case 1 and Case 3. Are there any?

Incidentally, this also implies that [Rising Waveform] (and its companions)
is legal only for Test_data_type = Single_ended and [Diff Rising Waveform]
is legal only for Test_data_type = Differential. I like this solution.
It's simple, and it covers the space defined by IBIS.

Al Davis proposed a new keyword, [Common Mode Rising Waveform Near], but my
gut reaction to this is negative. First, I want to close the BIRD since
it's been on the table a long time and is holding up IBIS 4.0. Second, it
seems somewhat verbose.

I propose that Cases 1 and 4 be legal but Cases 2 and 3 be illegal. Any
objections?

Greg Edlund
Electrical Packaging
IBM Server Technology Development
3605 Hwy. 52 N, Dept. HDC
Rochester, MN 55901
gedlund@us.ibm.com

 
Received on Fri Jul 13 06:36:41 2001