User Guide

Explorin
g
the Effect of Parameter and Specification Chan
g
es 3
-21
• Add new or edit existing parameter definitions and
specification descriptions.
Testin
g
Performance when
Chan
g
in
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Current Values
In the PSpice Optimizer window, you can quickly examine the
effects of a small change to either a parameter’s current value or
a specification’s current value.
Recalculation modes
When changing current values,
you can choose between automatic and manual recalculation of
performance.
• With automatic recalculation selected, you can change the
current value (upper text box) for one parameter or a
specification value, and see the impact on other values
almost immediately.
• With manual recalculation selected, you can change the
current value for several parameters or specifications, and
initiate recalculation when you are ready.
Derivative calculations
When tweaking values, the
PSpice Optimizer does not perform any simulations. Instead, the
optimizer requires derivative data and uses this to estimate what
will happen when you change a parameter or specification.
The PSpice Optimizer calculates derivatives either:
• once, when you select Update Derivatives from the Tune
menu, or
• for each iteration of an optimization run, when you select
Auto from the Tune menu.
Use the first method (Update Derivatives) when you are
exploring design tradeoffs.
See Derivatives on page 4-10 for
more information on how the
PSpice Optimizer computes
derivative data. See
Viewing
Derivatives on page 3-28 for
instructions on how to display the
latest derivative data.