Re: Modelling bus switches and other series elements

Bonjour,

I like Chris's suggestion. So we could have a keyword [Series Models]
followed by optional [State] keywords.

Let's be careful about the word "switch". There is the case
where a switch is ON or OFF, and then there's the case where different
paths are switched in or selected.

So [State] indicates when to use the ON model of a buffer.
In all other states, the OFF model is used.
i.e.[State] is used when there are selectable paths.

Example:

 [Series Models]
 | Pin Pin Model
    6 7 FET #always ON
 
 [State] StateName1
 | Pin Pin Model
    1 3 SMC #ON only when state=StateName1
 
 [State] StateName2
 | Pin Pin Model
     1 5 SMCx
 

Some questions:

  1) I see from the minutes of the last meeting that Arpad is
     preparing a BIRD on this subject. Is a draft of this BIRD
     available?

  2) A common application of bus switches is to protect
     components e.g. 3.3V from 5V, 2.5V from 3.3V.
     Should IBIS allow this to be modelled? Or is it
     too much an analog funcction?

Regards to all,
John Fitz

-- 
John Fitzpatrick   <John.Fitzpatrick@ln.cit.alcatel.fr>    
Alcatel Telecom, 4 rue de Broglie, 22304 Lannion, France
Tel: +33(0)2.96.04.79.33  Fax: +33(0)2.96.04.85.09
Chris Reid wrote:
> 
> Good morning,
> 
> Maybe instead of a syntax that defines all possible connections
> simultaneously (making it look like there are many simultaneous
> paths) we should find one that clearly calls out the different
> switch states.  Something like:
> 
> [State] StateName1
> | Pin   Pin   Model
>    1     3    SMC
> 
> [State] StateName2
> |  Pin   Pin   Model
>     1     5    SMCx
> 
> I'm not suggesting this as the actual syntax, only as an example
> to explain my concept.  The simulator must be told witch state of
> the switch to use in any particular simulation.
> 
> Of course, if the goal is to model the transition between states
> this is not helpful.  However, users of our system have not asked
> for that capability, but they have done things like Richard Mellitz
> suggests, swapping out one model for another, manually.
> 
> This syntax would give the user a way to specify the different
> switch states.  It would be up to the simulator to allow the
> user to specify whitch state to use when.
> 
> The same, or a degenerate syntax without the [State] specified
> could be used for series elements that are not switchable.
> 
> Chris Reid