Fwd: Re: Non-Monotonic Drivers

-- [ From: Ron Christopher * EMC.Ver #2.10P ] --

Forwarding to the reflector.

Ron Christopher
------- FORWARD, Original message follows -------

> Date: Tuesday, 22-Aug-95 09:32 PM
>
> From: Arpad Muranyi \ Internet:
> (arpad_muranyi@ccm.fm.intel.com)
> To: Ron Christopher \ PRODIGY: (EGJJ77A)
>
> Subject: Re: Non-Monotonic Drivers
>
> Text item:
>
> John,
>
> Thanks for the graphical response to my question. This is the kind
of
> response I really wanted to get. I have a question, though. Is
this I-V
> curve a function of the voltage on the output pin, or time. I mean,
is
> "translating between two Vgs curves" done with a feedback circuit by
> monitoring the output voltage, or is it a function of time as slew
rate
> controlled devices usually do it?
>
> If the answer is time, IBIS can definitely do it, but if it is
voltage (as
> in feedback), IBIS would not be able to help you at this time.
However,
> the open forum committee did consider this issue in meetings before,
and
> I don't think that it would be impossible to incorporate features
that
> can model it.
>
> Arpad
>
=======================================================================
==
> =====
> Arpad,
>
> The drivers Ron refers to have the following IV curve shape...
>
> Ids * *
> * *
> * *
> * *
> * ****************
> *
> *
> *
> * Vds
>
>
> Instead of the normal transistor curve shape like...
>
> Ids * ***********************
> *
> *
> *
> *
> *
> *
> *
> * Vds
>
>
> The top curve comes about because we are manipulating the gate
voltage to
> control di/dt noise in the maximum Vds region of the large output
device.
> Essentially we are translating between two Vgs curves for the output
> transistor. Hence the non-monotonicity is real and not noise related.
> Clamp diodes would add another bend in the curve and create 3 current
> values for 1 voltage value.
>
> The simulation tools we looked at would "correct" the data by making
the
> top curve look like the bottom. We saw some extreme differences in
> benchmark nets after this manipulation from the full transistor
> simulation. Since there is no standard on how to "correct" the above
> curve, we would not know how various simulation vendors would treat
the
> model.
>
> The above and the time schedule of IBIS 2.1 and CMOS 4 makes
supporting
> the IBIS modeling strategy unattractive for our CMOS 4 products.
>
> Thanks,
> John Brennan
>
>
***********************************************************************
> John Brennan Internal: jbrennan@btv
> IBM Microelectronics Internet:
jbrennan@vnet.ibm.com
> G77V/862-1 Tel: 802-769-6982 (Tie-Line:
446)
> Burlington, VT Fax: 802-769-5882 (Tie-Line:
446)
>
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> From: "John Brennan" <jbrennan@VNET.IBM.COM>
> Date: Tue, 22 Aug 1995 13:34:03 -0400
> Subject: Non-Monotonic Drivers
> To: EGJJ77A@prodigy.com, arpad_muranyi@ccm.fm.intel.com, jonp@qdt.com
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Received on Thu Aug 31 08:55:39 1995