EVA, extreme value analysis:

In this analysis
(actual EVA.SCP file), we change each parameter value to its extreme tolerance value such that the scalar measurements are maximized. Only parameters that have tolerances are altered. The extreme value for each tolerance with respect to a measurement is based on the sign of the previously run sensitivity analysis. The simulation is then run with those new parameter values that should maximize the scalar measurement value and the result for that measurement is saved in the "evahi" plot. The process is repeated for each measurement and when all the simulations are finished, the measurements are printed to the IsSpice4 output file in a format that can be read back in by SpiceNet. Additionally, the output file contains a summary report for your records. If you don't want make an evalo analysis, you can set the measurement min/max test limits by expanding the measurements to pass with symmetry in the Results dialog; as shown below.

The extreme value in this analysis refers to the parameters, not the resultant measurements. For most moderately complex circuits, the extreme value of the resultant measurement occurs when some of the parameters are at an intermediate rather than an extreme value. However, we usually find that EVA results produce wider measurement test limits than Monte Carlo — making it a worthwhile investment. Finding the true extreme value of the resulting measurements requires solution of a multi-parameter optimization problem. This becomes nearly impossible for larger circuits because the number of simulations grows as the product of parameters times the vectors. The EVA in this script runs an analysis for each toleranced parameter to get perturbation results and another for each measurement to get the final results.