Subject: About ibischk2+

From: [email-masked]
Date: Mon, 18 May 1998 10:21:26 +0900

Dear All,

I checked IBIS models by ibischk2+.
I have two questions.
Could you support me ?

1) Dose ibischk2+ make errors when IV table is non-monotonic? 
2) Why dose not ibischk2+ use "R_dut" value?  

---- Example of "1)" ---------------------------------------------------------
WARNING (line   47) - Pulldown Typical data is non-monotonic
WARNING (line   49) - Pulldown Maximum data is non-monotonic        <- 
WARNING (line  143) - Pullup Maximum data is non-monotonic
WARNING (line  183) - Pullup Minimum data is non-monotonic
WARNING (line  185) - Pullup Typical data is non-monotonic
WARNING - Model 'Buffer1': TYP AC Falling Endpoints ( 0.87V,  3.30V) not within 
          0.049V (2%) of ( 0.77V,  3.30V) on VI curves for 50 Ohms to 3.3V
WARNING - Model 'Buffer1': MIN AC Falling Endpoints ( 0.93V,  3.28V) not within 
          0.047V (2%) of ( 0.84V,  3.29V) on VI curves for 50 Ohms to 3.3V
WARNING - Model 'Buffer1': MAX AC Rising Endpoints (-0.00V,  1.85V) not within 
          0.037V (2%) of (-13.50V,  1.87V) on VI curves for 50 Ohms to 0V
                          ???????
WARNING - Model 'Buffer1': MAX AC Falling Endpoints ( 0.81V,  3.30V) not within 
          0.050V (2%) of (-15.70V,  3.30V) on VI curves for 50 Ohms to 3.3V
                          ???????
Errors  : 0
Warnings: 9
----------------------------------------------------------------------------------

Pulldown Maximum data corrected.

WARNING (line   47) - Pulldown Typical data is non-monotonic
WARNING (line  143) - Pullup Maximum data is non-monotonic
WARNING (line  183) - Pullup Minimum data is non-monotonic
WARNING (line  185) - Pullup Typical data is non-monotonic
WARNING - Model 'Buffer1': TYP AC Falling Endpoints ( 0.87V,  3.30V) not within 
          0.049V (2%) of ( 0.77V,  3.30V) on VI curves for 50 Ohms to 3.3V
WARNING - Model 'Buffer1': MIN AC Falling Endpoints ( 0.93V,  3.28V) not within 
          0.047V (2%) of ( 0.84V,  3.29V) on VI curves for 50 Ohms to 3.3V
WARNING - Model 'Buffer1': MAX AC Falling Endpoints ( 0.81V,  3.30V) not within 
          0.050V (2%) of ( 0.70V,  3.30V) on VI curves for 50 Ohms to 3.3V
                           ^^^^^
Errors  : 0
Warnings: 7
--------------------------------------------------------------------------------
  
Best regards.

Shigeto Nakajima
NEC Corpration

[email-masked]

---

From: Stephen Peters <[email-masked]>
Date: Mon, 18 May 1998 17:03:29 -0700

Hello Nakajima-san:

    My answers are below.  I hope this helps.

               Best Regards,
               Stephen Peters
               Intel Corp.

> 1) Dose ibischk2+ make errors when IV table is non-monotonic? 

      The ibischk2+ program checks for non-monotonic data because many 
simulators
      will not accept non-monotonic I/V data.  Please note however these are 
warnings,
      not errors.  Also be aware that the non-monotonic data may be in the 
result of
      subtracting the power/gnd clamp current from the pullup and pulldown 
currents,
      and that once the two curves are summed together (as the simulator will 
do) the
      data may be monotonic.  

      I notice that there are also warning that indicate that the V/T curves 
in your
      model do not settle to within 2% of the final DC value predicted by the 
I/V
      curves.  This may require some investigation.

> 2) Why dose not ibischk2+ use "R_dut" value?  

      The R_dut value represents part of the test load used when extracting the
      V/T curves.  It is included to document the test/extraction conditions.