RE: [IBIS-Users] IV table voltage range for min max and typ corners

For the I-V curves you should use these sweep ranges
with respect to GND:
 
typ:  -3.3 to 6.6
min:  -3.6 to 6.3
max:  -3.0 to 6.9
 
i.e. always 6.6 below, and 3.3 above Vcc, whatever Vcc
happens to be (typ/min/max).  Alternately you can also
do 7.2 below and 3.6 above Vcc but that is not really
required.
 
Regarding V-t curves, Rref is not what you need to
be concerned about.  R_fixture and V_fixture is the
important thing.  The rule of thumb is to select
an R_fixture that matches the impedance the buffer
was designed to drive or something that allows the
waveform to cross Vmeas.
 
Rref is used for a different purpose.  It is part of
a load which was used to measure the device's Tco
delay to reach Vmeas.
 
Arpad
=======================================================
 


________________________________

From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Sudarshan H N
Sent: Thursday, October 11, 2007 10:23 AM
To: ibis-users@server.eda.org
Subject: [IBIS-Users] IV table voltage range for min max and typ corners


Hi Experts,

In IV tables (clamps, pullup and pulldown), how do we normalize the voltage range correspoding to typical votage.
If we take 3.3 V domain, we need to simulate for -3.3 to 6.6 for typical case, -3 to 6 for min and - 3.6 to 7.2 in max.
Do we need to extrapolate the values in case min corner to get 3.3 to 6.6 range ?

With respect to V-t curves, we can take Rref as 50 ohm and generate the V-t curves. But the settling voltage may be less 
than the Vmeas (half of Pad voltage) (in case of rising waveforms). Is it acceptable ?

Let me know your answers.


Regards
Sudarshan

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