eldo_user

Setting Up An Analysis
Worst Case Analysis
The minimum and maximum waveforms correspond to the waveform envelope across all
Monte Carlo runs, not to a specific run. The minimum waveform is annotated _L in EZwave,
and the maximum waveform is annotated _H. For example:
.MC 10
.plot ac vdb(out)
This generates three waveforms:
• VDB(OUT): nominal run
• VDB(OUT)_L: minimum of v(out) across all 11 Monte Carlo runs (including nominal)
• VDB(OUT)_H: maximum of v(out) across all 11 Monte Carlo runs (including nominal)
See Also
• .MC in the Eldo Reference Manual
• Eldo Monte Carlo Quick Start
Related Topics
Monte Carlo Analysis
Worst Case Analysis
Worst Case analysis (.WCASE command) is a corner analysis that computes worst-case values
for waveform data extracted using the .EXTRACT command according to a set of Monte Carlo
parameters that have LOT and DEV variations.
Considering a design which contains P parameters that have a statistical variation, and T targets
(.EXTRACT commands), Eldo will perform several simulations:
1. The first simulation is the nominal simulation, using nominal values for the P
parameters.
2. Next P simulations are sensitivity analysis runs, where Eldo applies a small variation to
one of the P parameters, keeping all other parameters to their nominal value, and
computes the sensitivity of the T targets relative to the current parameter.
For each of the T targets, Eldo outputs a message like:
With respect to MODEL R LOT
Variation of MAX(V(1)) is negative: -1.000000e-02 (Unit/%) or
1.000000e+00 (%/%)
Negative variation means that when parameter is increased, target is decreasing.
Eldo® User's Manual, 15.3 267