Understanding Warning and Error Messages

If certain conditions are met (or not met), Star-Hspice prints warnings or error messages. Some examples of these messages are described below.

Warnings are issued if Star-Hspice determines that the input data are inconsistent. In this case, Star-Hspice modifies data to make consistent and runs the simulation with modified data. Static I/V curves take precedence over V(t) curves and ramp data. If data are modified by Star-Hspice, it is unlikely the results of simulation with a test load will match V(t) curves given in the IBIS file. To achieve high accuracy, input data should be consistent. Pay close attention to warnings and understand the causes.

Errors are issued if Star-Hspice determines that the run can not be continued with the given data.

Example

An example of a warning:

** warning** iob_eles2:205:

text of the warning, line1

text of the warning, line2

An example of an error:

** error** iob_eles2:205:

text of the error, line1

text of the error, line2

Text that follows the comments ' ** warning** ' and ' ** error** ', such as ' iob_eles2:205: ' identifies the location where the problem occurs. It is intended to help the developer solve the problem.

The following information is intended for users. A list of selected warnings follows.

1. I/V Curves
PC and GC I-V curves should be equal to zero at zero voltage, I(V=0)=0. If different values are found, a warning is issued. For example, for a PC I/V curve the following warning is issued.

** warning** ffffffff:NNN:

POWER_Clamp curve should be zero at origin

found value 1.85800E-01

I/V curve is not modified

This warning occurs for Power_Clamp and Ground_Clamp I/V curves. Star-Hspice takes these I/V curves as given but an error is likely to occur if I(V=0) is not zero.

2. I-V curves and rising/falling waveforms (RWF, FWF) should be consistent. Star-Hspice verifies consistency for the end points of RWF, FWF. If inconsistency is detected, the I/V curves take precedence over V(t) curves, and V(t) curves are modified to make them consistent with I-V curves.

** warning** ffffffff:NNN:

Falling WF min estimate and given value differ

estimate = 3.3540E-01 given = 6.6000E-01

In this example, I/V curves give a value of 3.3540E-01V for minimum voltage when pullup is OFF (if pullup is available) and pulldown is ON (if pulldown is available) for load specified for FWF. The minimum voltage value of FWF in the IBIS file is 6.6000E-01V. In this case, the FWF is modified by Star-Hspice to be consistent with I-V curves.

3. I/V curves and ramp data should be consistent (if ramp is used). Star-Hspice verifies consistency for end points of rising edge and falling edge. The IBIS standard requires that ramp data correspond to 20% to 80% transition of the total voltage change. If inconsistency is detected, the following warning is given.

** warning** ffffffff:NNN:

Inconsistency between Ramp and PD/PU data is detected.

dV_r= 1.5900E+00 V_rwf_max= 3.3000E+00 V_rwf_min= 3.3540E-01

transition from 20% to 80% is not satisfied

FILE = gtl-plus.ibs

MODEL = io_buf

In this example, voltage changes from 0.3354 V to 3.3 V on the rising edge, as calculated from I/V curves. 60% of this range is 1.78 V. The IBIS file gives 1.59 V. Star-Hspice gives warnings, takes derivative for ramp as given in the IBIS file and the voltage range as calculated from I/V curves.