User Guide

Checkin
g
that the Desi
g
n Will Simulate 5
-11
Checkin
g
that the
Desi
g
n Will Simulate
Before running a full optimization, you should run a single
iteration to make sure the design still simulates (by selecting
Update Performance from the Tune menu). The PSpice
Optimizer performs the simulations and trace function
evaluations required to find the current value for each active
specification, and updates their initial values.
For this example, an initial iteration has already been run. The
Vc specification shows 2.5 and the Rt specification shows 250
in the initial value fields. Note that this example requires one
PSpice simulation to update the performance.
Startin
g
the
Optimization
You are now ready to run the full optimization to find resistor
values which satisfy the two specifications (output voltage 3.75
V, equivalent resistance 100 Ω).
To start optimizin
g
1
From the Tune menu, select Auto and click Start.
First, the PSpice Optimizer computes the derivative of each
specification with respect to each parameter at the initial
value. While this is in progress, the message
Updating
Derivatives
appears in the status bar of the optimizer
window. In this example, two simulations are performed—
one for each parameter.
Using the derivative information, the optimizer selects a
direction in which to vary the parameters. The optimizer
tries parameter changes along this direction until it achieves
a reduction in the overall error. The optimizer then updates
the parameters, and computes new derivatives.
initial
value