[ibis-interconn] Mixed Mode, understanding the simple case

  • From: "Walter Katz" <wkatz@xxxxxxxxxx>
  • To: <ibis-interconn@xxxxxxxxxxxxx>
  • Date: Wed, 18 Jun 2008 16:55:28 -0400

All,

Consider a simple differential line consisting of near end ports N+ and N-,
and far end ports F+ and F-. A singled ended s4p model might have the
following port assignments:

Port # Port Name
1                           S(N+)
2                           S(N-)
3                           S(F+)
4                           S(F-)
[Interconnect Port Groups] (S(1):S(3)) (S(2): S(4))

I do understand that mixed mode representation goes beyond near/far end
interconnect, but I will assume this for the purpose of this discussion.

I had earlier proposed the following enhancement to  [Interconnect Port
Groups] to allow description of near/far end differential interconnect

[Interconnect Port Groups] (S(1,2):S(3,4))
(S(1,2):S(3,4))is interpreted as Single Ended
port 1 is near end active high
port 2 is near end active low
port 3 is far end active high
port 4 is far end active low

It would be straightforward to convert this single ended s4p to a mixed mode
s4p:


Port # Port Name
1                           D(N+,N-)
2                           C(N+,N-)
3                           D(F+,F-)
4                           C(F+,F-)
[Interconnect Port Groups] (DC(1,2):DC(3,4))

(DC(1,2):DC(3,4))is interpreted as
port 1 is near end differential mode
port 2 is near end common mode
port 3 is far end differential mode
port 4 is far end common mode


There is no need to assume near and far end in this context. The following
is a valid representation of both the single ended and mixed mode data:

Single ended:
[Interconnect Port Groups] S(1,2) S(3,4)

Mixed mode:
[Interconnect Port Groups] DC(1,2) DC(3,4)

Hybrid
[Interconnect Port Groups] DC(1,2) S(3) S(4)
[Interconnect Port Groups] (DC(1,2):S(3),S(4))

And three port ?differential? is just as easy
Single Ended
[Interconnect Port Groups] S(1,2,3)
Mixed mode:
[Interconnect Port Groups] D12D13C(1,2,3)
[Interconnect Port Groups] D12D13D23(1,2,3)
D12 is differential 1,2
D13 is differential 1,3
D13 is differential 2,3
C is common mode 1,2,3


Why does this not address all of the issues that we have been discussing?

Walter

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