Re[4]: IBIS Open Forum 1/6/95 Meeting Minutes

Text item:

Kumar,

Now I am starting to understand your thought process. However, I don't agree
with your suggestion, quote: "For a practically meaningful v-i verification...
...compare the resulting v-t with some reference waveform".

If you are trying to verify the I-V curve, don't use waveforms, because the
waveforms are not directly effected by the I-V curve. Waveforms are dependent
on rise/fall times, transmission line models (lossy or lossless), T-line length,
load capacitances, etc... None of which have much to do with DC. The only
thing you can do to verify an I-V curve is to look at the ledge voltage (if you
have a distinct one) of a waveform. However, you can get the same ledge voltage
with a pure resistor as the load (if its value represents your loading
impedance). Once you are at this point, you might as well just match the I-V
curve to a known Referece I-V curve, and be done.

Arpad

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

By standard load, I waa trying to indicate the following.

The ac v-t specifications include loads under whcih the measurements
were taken.
So if the siumulations reproduce the v-t behavior at those load conditions
then
they are self verifying and are pracically meaningful.

For a practically meaningful v-i verification, we have to drive a
reference load with the
device and then compare the resulting v-t with some reference waveform.
What is a useful refernce load. Is it daisy chain transmission line
with ten loads? Or is it a simple capacitor? In the past we have been
unable to come to agreement on identifying both the reference load
and waveforms.

This is what I meant by refernce loads for v-i verification.
>
> Kumar,
>
> I am still not sure what you mean by "standard load". When you
do a voltage
> sweep on a device, you are forcing the voltage while you are measuring the
> current. When yo do this sweep, you are actually "loading" the
device with the
> voltage source. You can look at that voltage source as an ideal,
0 Ohm source
> or as a Thevenin combination of an ideal source with a series resistor.
 Either
> way, you are sweeping between a certain voltage range at the output of the
> device to get an I-V curve, regardless of what R is in your Thevenin
circuit.
> Your I-V curve will be the same whether R in the Thevenin circuit
is small or
> large. You will just have to increase the sweep range of the voltage
source
> inside the Thevenin circuit for larger R values to get the same
sweep range at
> the pin of the device.
>
> What is the probelem? Am I missing something obvious?
>
> Arpad
>
> -----------------------------------------------------------------------------
-
>
> The problem with I-V checking is that there is no "standard" load as
> with V-T curves. We already went through this i-v standard load discussion
> and dropped it because
> of controvorsey. The reason I raised it because that I think that in
> signal integrity situations the dc I-V characteristic has more has
a dominant
> effect on the resulting waveforms and we have no reference to check against.
>
> >
> > Hello IBIS gurus,
> >
> > In the last minutes Kumar suggested DC checking (see quote below).
 I am not
> > sure what he means, but just as we can use V-T tables for AC checking,
> couldn't
> > the I-V curves be used for DC checking?
> >
> > Arpad
> > Intel Corporation
> >
> >
> > > Compliance
> > > Will pointed out that the V/T table can be used to as a type
of compliance
> > > test/sanity check. Kumar would like to see a DC check as well.
> >
> > > AR Kumar: Post an EGG for DC checking.
> >
> >
> > Text item: External Message Header
> >
> > The following mail header is for administrative use
> > and may be ignored unless there are problems.
> >
> > ***IF THERE ARE PROBLEMS SAVE THESE HEADERS***.
> >
> > Subject: IBIS Open Forum 1/6/95 Meeting Minutes
> > To: Randy_L_Wilhelm@ccm.fm.intel.com, Jerry_Budelman@ccm2.jf.intel.com,
> > bWard@neosoft.com, IBIS@vhdl.org
> > Message-Id: <950113103507_2@ccm.hf.intel.com>
> > From: Derrick Duehren <Derrick_Duehren@ccm2.jf.intel.com>
> > Date: Fri, 13 Jan 95 10:35:07 PST
> > Received: by ccm.hf.intel.com (ccmgate 3.0) Fri, 13 Jan 95 10:35:07 PST
> > Received: from ccm.hf.intel.com by relay.jf.intel.com
> > (Smail3.1.28.1 #2) id m0rSqq5-000twhC; Fri, 13 Jan 95 10:35 PST
> > Received: from relay.jf.intel.com by ormail.intel.com with smtp
> > (Smail3.1.28.1 #7) id m0rSqq7-000Ug3C; Fri, 13 Jan 95 10:35 PST
> > Received: from ormail.intel.com by vhdl.vhdl.org (4.1/SMI-4.1/BARRNet)
> > id AA09335; Fri, 13 Jan 95 10:40:26 PST
> > Received: from vhdl.vhdl.org by hermes.intel.com (5.65/10.0i); Fri,
> 13 Jan 95 10
> > Received: from hermes.intel.com by relay.jf.intel.com with smtp
> > (Smail3.1.28.1 #2) id m0rSrDN-000twfC; Fri, 13 Jan 95 10:59 PST
> >
>
> Text item: External Message Header
>
> The following mail header is for administrative use
> and may be ignored unless there are problems.
>
> ***IF THERE ARE PROBLEMS SAVE THESE HEADERS***.
>
> Subject: Re: IBIS Open Forum 1/6/95 Meeting Minutes
> To: ibis@vhdl.org, Arpad_Muranyi@ccm.fm.intel.com
> Message-Id: <9501171455.AA14781@hot>
> From: cpk@cadence.com (C. Kumar)
> Date: Tue, 17 Jan 95 09:55:15 -0500
> Received: by hot (5.65+/1.5)
> id AA14781; Tue, 17 Jan 95 09:55:15 -0500
> Received: from hot by cadence.Cadence.COM (5.61/3.14)
> id AA05113; Tue, 17 Jan 95 06:54:58 -0800
> Received: from cadence.cadence.com(158.140.18.1) by mailgate.cadence.com
via sma
> id sma028434; Tue Jan 17 06:55:24 1995
> Received: (from smap@localhost) by mailgate.Cadence.COM (8.6.8/8.6.8)
id GAA2844
> Received: from mailgate.Cadence.COM by vhdl.vhdl.org (4.1/SMI-4.1/BARRNet)
> id AA29044; Tue, 17 Jan 95 07:00:29 PST
> Received: from vhdl.vhdl.org by aurora.intel.com (5.65/10.0i); Tue,
17 Jan 95 07
> Received: from aurora.intel.com by relay.jf.intel.com with smtp
> (Smail3.1.28.1 #2) id m0rUFcT-000tweC; Tue, 17 Jan 95 07:14 PST
>

Text item: External Message Header

The following mail header is for administrative use
and may be ignored unless there are problems.

***IF THERE ARE PROBLEMS SAVE THESE HEADERS***.

Subject: Re: Re[2]: IBIS Open Forum 1/6/95 Meeting Minutes
To: ibis@vhdl.org, Arpad_Muranyi@ccm.fm.intel.com
Message-Id: <9501171904.AA14945@hot>
From: cpk@cadence.com (C. Kumar)
Date: Tue, 17 Jan 95 14:04:03 -0500
Received: by hot (5.65+/1.5)
        id AA14945; Tue, 17 Jan 95 14:04:03 -0500
Received: from hot by cadence.Cadence.COM (5.61/3.14)
        id AA18883; Tue, 17 Jan 95 11:03:39 -0800
Received: from cadence.cadence.com(158.140.18.1) by mailgate.cadence.com via sma
        id sma021981; Tue Jan 17 11:04:13 1995
Received: (from smap@localhost) by mailgate.Cadence.COM (8.6.8/8.6.8) id LAA2199
Received: from mailgate.Cadence.COM by hermes.intel.com (5.65/10.0i); Tue, 17 Ja
Received: from hermes.intel.com by relay.jf.intel.com with smtp
        (Smail3.1.28.1 #2) id m0rUJF6-000tweC; Tue, 17 Jan 95 11:07 PST
Received: from relay.jf.intel.com by relay.hf.intel.com with smtp
        (Smail3.1.28.1 #2) id m0rUJF7-000qDpC; Tue, 17 Jan 95 11:07 PST
Received on Tue Jan 17 16:32:00 1995