Re: How to correct the monotonicity problem of ibis model whenimporting model to ICX?

Olli:

I will respond briefly to your questions.

For non-monotonic data problem, it appears that your
suggestion of just zeroing out the noisy data should
eliminate the Error reports. This approach should not
effect accuracy. There may be other options that could
be discussed directly with the vendor.

There probably is not a completely general answer for
selecting a Vmeas when none can be found. It is needed
if any timing delay data is specified. My first
approach would be to select a value that is somewhere
midway between the input threshold voltages for the
input techology that the I/O buffer is designed to
drive.

Best Regards,
Bob Ross
Mentor Graphics

Olli Timonen wrote:
>
> Hello!
>
> I tried to import an ibis model to ICX. It reports following errors of non
> monononicity:
>
> Error: The sum of the typical clamp curves is not monotonic at voltage 1.6
> Error: The sum of the minimum clamp curves is not monotonic at voltage 2.1
> Error: The sum of the maximum clamp curves is not monotonic at voltage 2.6
>
> !! the model in question is in the end of this message !!
>
> What is the best way to modify this model to make it compatible with ICX? Does
> simulation distort significantly if I just change all the I-values to zeros
> after voltage has turned positive?
>
> Second question:
>
> What is the good (best) way to define Vmeas value if it isn't included in the
> model and can't be found from the datasheets, etc. (maybe Vdd*0.5?)?
>
> ********************************************************
>
> [Model] ptic
> Model_type Input
> Polarity Non-Inverting
> Enable Active-Low
> Vinl = 0.8000V
> Vinh = 2.000V
> C_comp 5.0pF 5.0pF 5.0pF
>
> [Temperature Range] 25.0000 85.000 -40.0000
> [Voltage Range] 3.3000V 2.9700V 3.6300V
> [GND_clamp]
> | voltage I(typ) I(min) I(max)
>
> -3.30 -0.761 -0.682 -0.999
> -3.20 -0.712 -0.641 -0.928
> -3.10 -0.664 -0.601 -0.859
> -3.00 -0.618 -0.563 -0.794
> -2.90 -0.574 -0.526 -0.731
> -2.80 -0.531 -0.49 -0.67
> -2.70 -0.49 -0.455 -0.612
> -2.60 -0.451 -0.421 -0.557
> -2.50 -0.413 -0.388 -0.504
> -2.40 -0.376 -0.357 -0.454
> -2.30 -0.342 -0.327 -0.407
> -2.20 -0.308 -0.298 -0.362
> -2.10 -0.277 -0.27 -0.319
> -2.00 -0.247 -0.244 -0.28
> -1.90 -0.219 -0.219 -0.243
> -1.80 -0.188 -0.191 -0.208
> -1.70 -0.166 -0.171 -0.172
> -1.60 -0.145 -0.151 -0.147
> -1.50 -0.124 -0.131 -0.123
> -1.40 -0.104 -0.112 -0.101
> -1.30 -0.0847 -0.0933 -0.0784
> -1.20 -0.0659 -0.0751 -0.0576
> -1.10 -0.0483 -0.0579 -0.0387
> -1.00 -0.032 -0.0416 -0.0221
> -0.90 -0.018 -0.027 -0.0099
> -0.80 -0.0079 -0.0147 -0.00469
> -0.70 -0.00311 -0.00627 -0.00265
> -0.60 -0.00144 -0.00228 -0.00121
> -0.50 -0.000504 -0.000854 -0.000315
> -0.40 -7.55e-05 -0.000237 -2.37e-05
> -0.30 -2.96e-06 -2.93e-05 -3.18e-07
> -0.20 -8e-08 -1.65e-06 -1.28e-08
> -0.10 -6e-09 -7.53e-08 -1.75e-09
> 0.00 -4e-09 -7.75e-09 3.25e-09
> 0.10 -1e-09 -2.5e-09 9.25e-09
> 0.20 -2e-09 2.5e-10 1.43e-08
> 0.30 -2.5e-09 -2.5e-10 1.57e-08
> 0.40 -4e-09 -7.5e-10 1.98e-08
> 0.50 -2.5e-09 -1e-09 2.2e-08
> 0.60 -2e-09 5e-10 2.7e-08
> 0.70 -3e-09 1e-09 3.12e-08
> 0.80 -1e-09 -1.5e-09 3.5e-08
> 0.90 -3e-09 -5e-10 3.98e-08
> 1.00 -2e-09 -7.5e-10 4.22e-08
> 1.10 -2e-09 -3.5e-09 4.5e-08
> 1.20 0 -1.96e-07 4.93e-08
> 1.30 -5e-09 -5.23e-06 5.1e-08
> 1.40 -2.99e-07 -1.05e-05 5.15e-08
> 1.50 -1.64e-05 -1.35e-05 -3.01e-06
> 1.60 -2.03e-05 -1.4e-05 -1.49e-05
> 1.70 -2.12e-05 -1.39e-05 -2.99e-05
> 1.80 -2.15e-05 -1.32e-05 -3.21e-05
> 1.90 -2.1e-05 -2.32e-05 -3.26e-05
> 2.00 -2.02e-05 -3.13e-05 -3.24e-05
> 2.10 -2e-05 -0.000108 -3.18e-05
> 2.20 -2e-05 -0.000168 -3.05e-05
> 2.30 -2e-05 -0.000152 -5.53e-05
> 2.40 -2e-05 -5.97e-05 -7.74e-05
> 2.50 -2e-05 -1.16e-05 -0.000134
> 2.60 -2e-05 -1.37e-06 -0.000245
> 2.70 -2e-05 -1.32e-07 -0.000562
> 2.80 -1.84e-06 -1.1e-08 -0.00048
> 2.90 -1.17e-07 1.25e-09 -0.000223
> 3.00 -1e-08 1.25e-09 -6.41e-05
> 3.10 -5.5e-09 2.5e-09 -9.3e-06
> 3.20 -1e-09 5e-09 -5.43e-07
> 3.30 -2e-09 1.05e-08 8.95e-08
>
> [POWER_clamp]
> | voltage I(typ) I(min) I(max)
>
> -3.30 0.388 0.281 0.525
> -3.20 0.365 0.264 0.494
> -3.10 0.343 0.248 0.464
> -3.00 0.321 0.232 0.434
> -2.90 0.3 0.216 0.406
> -2.80 0.28 0.2 0.378
> -2.70 0.26 0.186 0.352
> -2.60 0.241 0.169 0.326
> -2.50 0.222 0.156 0.301
> -2.40 0.204 0.144 0.277
> -2.30 0.187 0.131 0.254
> -2.20 0.168 0.119 0.233
> -2.10 0.154 0.107 0.212
> -2.00 0.14 0.0948 0.192
> -1.90 0.127 0.0828 0.169
> -1.80 0.113 0.071 0.153
> -1.70 0.101 0.0595 0.138
> -1.60 0.0876 0.0484 0.122
> -1.50 0.0748 0.0377 0.107
> -1.40 0.0625 0.0279 0.0935
> -1.30 0.0507 0.019 0.0796
> -1.20 0.0396 0.0116 0.0665
> -1.10 0.0295 0.00559 0.0543
> -1.00 0.0205 0.00106 0.0428
> -0.90 0.0127 0.000111 0.0321
> -0.80 0.00535 8.34e-06 0.0219
> -0.70 0.000761 7.24e-07 0.013
> -0.60 4.39e-05 1.12e-07 0.00507
> -0.50 1.37e-06 2.93e-08 0.000549
> -0.40 4.5e-08 1.05e-08 2.08e-05
> -0.30 0 5e-09 4.82e-07
> -0.20 -1e-09 2.5e-09 1.48e-07
> -0.10 -2.5e-09 1.25e-09 1.34e-07
> 0.00 -2e-09 1.25e-09 1.29e-07
Received on Wed May 10 10:12:17 2000