User`s guide

3
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14 Preparin
g
a Schematic for Simulation
Usin
g
Global
Parameters and
Expressions for Values
In addition to literal values, you can use global parameters and
expressions to represent numeric values in your circuit design.
Global Parameters
A global parameter is like a programming variable that
represents a numeric value by name.
Once you have defined a parameter (declared its name and given
it a value), you can use it to represent circuit values anywhere in
the schematic; this applies to any hierarchical level.
Some ways that you can use parameters are as follows:
• Apply the same value to multiple part instances.
• Set up an analysis that sweeps a variable through a range of
values (for example, DC sweep or parametric analysis).
Declarin
g
and usin
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a
g
lobal parameter
To use a global parameter in your schematic, you need to:
• define the parameter using a PARAM symbol, and
• use the parameter in place of a literal value somewhere in
your design.
When multiple parts are set to
the same value,
g
lobal
parameters provide a convenient
way to chan
g
e all of their values
for “what-if” analyses.
Example: If two independent
sources have a value defined by
the parameter VSUPPLY, then
you can chan
g
e both sources to
10 volts by assi
g
nin
g
the value
once to VSUPPLY.