Subject: problem with a model

From: Olli Timonen <[email-masked]>
Date: Fri, 11 Aug 2000 12:21:45 +0300

Hi!

I have a problem with one IBIS model. The current of a pulldown starts
to decrease after about 5V. How is this possible? What causes this kind
of occurrences and is there any kind of solutions to fix this kind of a
model?

The [Pulldown] of a model in question is below.

Regards,
Olli

|************************************************************************

|                             Model Buffer
|************************************************************************

|
[Model]          Buffer
Model_type       3-state
Polarity         Non-Inverting
Enable           Active-High
Vinl =   0.00V
Vinh =   5.00V
C_comp           5.00pF              5.00pF              5.00pF
|
|
[Temperature Range]       25.00               100.00              -40.00

[Voltage Range]           5.00V               4.50V               5.50V
[Pulldown]
| voltage     I(typ)              I(min)              I(max)
|
  -5.00     -1000.00uA          -1000.00uA             0.00A
  -4.60        0.00A               0.00A               0.00A
  -4.20       -1.00mA             -1.00mA           -1000.00uA
  -3.80       -1.00mA              0.00A              -1.00mA
  -3.40       -1.00mA              0.00A              -1.00mA
  -3.00     -1000.00uA          -1000.00uA            -1.00mA
  -2.60     -1000.00uA          -1000.00uA            -2.00mA
  -2.20       -1.00mA              0.00A              -2.00mA
  -1.80       -2.00mA             -2.00mA             -3.00mA
  -1.40       -3.50mA             -2.00mA             -5.80mA
  -1.00      -10.70mA             -4.60mA            -37.60mA
  -0.90      -19.70mA             -6.50mA            -83.83mA
  -0.80      -43.09mA            -10.50mA            -93.72mA
  -0.70      -53.81mA            -20.14mA            -85.15mA
  -0.60      -48.13mA            -28.69mA            -75.24mA
  -0.50      -41.67mA            -26.51mA            -65.04mA
  -0.40      -34.83mA            -22.15mA            -54.70mA
  -0.30      -27.32mA            -17.29mA            -43.21mA
  -0.20      -19.06mA            -12.00mA            -30.38mA
  -0.10      -10.00mA             -6.25mA            -16.04mA
   0.00        0.00A               0.00A               0.00A
   0.10       10.61mA              6.62mA             16.95mA
   0.20       21.06mA             13.28mA             33.15mA
   0.30       31.04mA             19.69mA             48.53mA
   0.40       40.58mA             25.83mA             63.11mA
   0.50       49.67mA             31.71mA             76.92mA
   0.60       58.31mA             37.32mA             89.97mA
   0.70       66.54mA             42.66mA            102.32mA
   0.80       74.33mA             47.74mA            113.91mA
   0.90       81.73mA             52.57mA            124.89mA
   1.00       88.71mA             57.14mA            135.18mA
   1.10       95.29mA             61.45mA            144.77mA
   1.20      101.53mA             65.51mA            153.85mA
   1.30      107.31mA             69.32mA            162.24mA
   1.40      112.70mA             72.88mA            170.12mA
   1.50      117.78mA             76.19mA            177.41mA
   1.60      122.47mA             79.26mA            184.09mA
   1.70      126.85mA             82.09mA            190.38mA
   1.80      130.83mA             84.68mA            196.06mA
   1.90      134.52mA             87.04mA            201.25mA
   2.00      137.90mA             89.16mA            206.03mA
   2.10      140.89mA             91.06mA            210.31mA
   2.20      143.57mA             92.73mA            214.20mA
   2.30      145.95mA             94.18mA            217.58mA
   2.40      148.04mA             95.40mA            220.56mA
   2.50      149.82mA             96.42mA            223.14mA
   2.60      151.30mA             97.23mA            225.32mA
   2.70      152.48mA             97.82mA            227.11mA
   2.80      153.47mA             98.21mA            228.59mA
   2.90      154.15mA             98.50mA            229.67mA
   3.00      154.53mA             98.79mA            230.45mA
   3.10      155.01mA             99.06mA            231.03mA
   3.20      155.29mA             99.28mA            231.51mA
   3.30      155.68mA             99.57mA            231.99mA
   3.40      156.06mA             99.85mA            232.46mA
   3.50      156.34mA            100.04mA            232.84mA
   3.60      156.62mA            100.23mA            233.32mA
   3.70      156.90mA            100.41mA            233.70mA
   3.80      157.18mA            100.60mA            233.98mA
   3.90      157.46mA            100.79mA            234.35mA
   4.00      157.64mA            100.97mA            234.63mA
   4.10      157.92mA            101.16mA            234.91mA
   4.20      158.11mA            101.35mA            235.09mA
   4.30      158.29mA            101.43mA            235.36mA
   4.40      158.47mA            101.62mA            235.54mA
   4.50      158.55mA            101.70mA            235.71mA
   4.60      158.73mA            101.79mA            235.79mA
   4.70      158.81mA            101.88mA            235.87mA
   4.80      158.89mA            101.96mA            235.94mA
   4.90      158.97mA            102.08mA            236.02mA
   5.00      159.05mA            101.98mA            236.09mA
   5.10      159.03mA            101.88mA            236.07mA
   5.20      159.01mA            102.00mA            236.04mA
   5.30      159.09mA            102.10mA            235.91mA
   5.40      159.04mA            102.20mA            235.89mA
   5.50      158.73mA            102.10mA            235.76mA
   5.60      158.13mA            102.20mA            235.64mA
   5.70      157.92mA            102.20mA            235.41mA
   5.80      158.36mA            101.80mA            235.28mA
   5.90      158.40mA            102.00mA            234.97mA
   6.00      158.40mA            102.00mA            234.25mA
   6.40      157.60mA            102.00mA            232.97mA
   6.80      158.00mA            102.00mA            232.20mA
   7.20      156.00mA            101.00mA            231.00mA
   7.60      156.00mA            101.00mA            230.00mA
   8.00      155.00mA            101.00mA            229.00mA
   8.40      155.00mA            101.00mA            228.00mA
   8.80      155.00mA            101.00mA            226.00mA
   9.20      154.00mA            100.00mA            225.00mA
   9.60      153.00mA            100.00mA            224.00mA
  10.00      153.00mA             99.00mA            222.00mA

---

From: Dan Aleksandrowicz <[email-masked]>
Date: Sun, 13 Aug 2000 17:32:51 +0200

Hi Olli.

In case you are using the s2ibis software it seems that you are
not using the correct version.
There is a fix that increases the resolution to 4 decimal points.
This is very important in pullup/pulldown curve which are
manipulated (curve reduction) by the s2ibis software.

The fix might do wonders to solve this issue.

However, another tip might be is to gently fine tune your Vinh/Vinl like:
[vil] 0.6 0.6 0.5
[vih] 1.6 1.6 1.6

This method did solve a lot of problems.

Also in case you are using Hspice I recommend removing ALL .options from
the spice file. You might be increasing the error tolerance to get
convergence.
Doing so will give such results.

For more tips and ideas you are welcome to contact me.

--
                \\|//
                (o o)
~~~~~~~~~~~~oOOo~(_)~oOOo~~~~~~~~~~~~~~~~~~~
Dan Aleksandrowicz
Galileo Technology
Mercaz Ofek 1   (Building B')
Northern Industrial Zone, LOD 71293,  ISRAEL
email:[email-masked]
Tel: +972 8 9247555    (-
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