Re: the 4 V-t curves of IBIS 2.1

Betty, this is from a seminar given by Mr. Arpad Muranyi from Intel, so
all rights are reserved to him :)

-------------------------------------------------------------------
What do we get in the I-V curves?
Digital buffers can only be measured in two modes (if not one)
* Receive or 3-state mode
  * allows us to measure the currents of
    parasitic diodes (for MOSFETS)
    ESD protection circuits
    pullup or pulldown "resistors"
    static overshoot protection clamps
    integrated static terminators
(comment by O.K.- the above are ALWAYS ON)

* Drive mode (driving high or low)
  * allows us to measure the currents of all of the above, plus
                                                           ----
    channel currents for pulldown and/or pullup structures
    dynamic clamps
    dynamic bus hold circuits
    integrated active terminators

BOTH MODES ARE NEEDED FOR SIMULATIONS

DRIVE/RECEIVE MODE TRANSITIONING
* Phase out "reciever model" as the "driver model" is phased in, or vive
versa
   It may be difficult to come up with an algorithm that can cross fade
   the two models so that the static currents remain constant during the
   transitioning process.

* Keep "receiver model" constantly in the circuit and phase in/out the
difference between the driver and receiver models
----------
   Note that a drive mode model includes the static currents of those
   circuit or device elements that make up a receive mode model because
   these are never turned off. These currents would be doubled if the
   drive mode model would simply be added to a receive mode model.

THE SECOND APPROACH IS USED IN IBIS.

---------------------------------------------------------------------

Hope this helped :)

Offer Kaye
sofferk@techst02.technion.ac.il
Web Site: http://t2.technion.ac.il/~sofferk

On Wed, 27 Sep 2000, Betty Luk wrote:

> Hello,
>
> Why do we need four V-t curves to describe the rising and falling edges of a CMOS buffer (as described in the IBIS cookbook)?
>
>
> Many thanks,
>
> Betty Luk
>
> IC Technology
> Genesis Microchip Inc.
> 165 Commerce Valley Dr. W.
> Thornhill, Ont. L3T 7V8
> (905) 889-5400 x2256
>
>

 
Received on Thu Sep 28 00:41:17 2000