What does Worst case Analysis do?

Worst Case is used to find the worst probable output of a circuit given the restricted variance of its parameters.

A sensitivity analysis is done for each parameter with a tolerance in turn to determine the “sensitive” direction for the parameter. Once the “sensitive” direction has been found for all of the components with a tolerance, a final worst case analysis is performed by setting all of the parameters to the limit of their tolerance in the “sensitive” direction.

The worst case is run in conjunction with another simulation, DC Sweep, AC Sweep or Transient and the simulation settings determine “where” to look for the worst case and “which direction” the worst case is. (It’s always possible to run two simulations if the worst case direction is in doubt)

Lab process

In the Labs, the first lab sequence will establish the worst case and then sweep a value parameter to confirm that the worst case simulation matches the worst case found. In the second lab sequence, the circuit is modified so that is no longer “linear”, the circuit is clipping, and the worst case is found. Then the sweep of the value parameter establishes that the worst case has found the same, “low going” direction for the worst case but the “real” worst case is in the “high going” direction. Indicating the the circuit should be properly evaluated before taking simulation results at face value.

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