Download Spectre Circuit Simulator User Guide

Spectre Circuit Simulator User Guide
Parameter Specification and Modeling Features
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Predefined circuit or subcircuit parameters
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Built-in constants (fixed values) or mathematical functions (software routines that
calculate equations)
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Real or integer constants
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The name of a component instance or model
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The name of a component parameter
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A character string (must be surrounded by quotation marks)
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A name from a predefined set of names available to specify the parameter value
(enumerated types)
Parameter Dimension
Component or analysis parameters can be either scalar or vector.
If a component or analysis parameter value is a group of numbers or names, you specify the
group as a vector of values by enclosing the list of items in square brackets ([])—for
example, coeffs=[0 0.1 0.2 0.5] to specify the parameter values 0, 0.1, 0.2, and
0.5. You can specify a group of number pairs (such as time-voltage pairs to specify a
waveform) as a vector of the individual numbers.
Remember these guidelines when you specify vectors of value:
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You can mix numbers and netlist or subcircuit parameter names in the same vector
(coeff=[0 coeff1 coeff2 0.5]).
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You cannot leave a list of items empty.
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You can use expressions (such as formulas) to specify numbers within a vector. When
you use a vector of expressions, each expression must be surrounded by parentheses
(coeff=[0 (A*B) C 0.5]).
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You can use subcircuit parameters within vectors.
Parameter Ranges
Parameter ranges have hard limits and soft limits. Hard limits are enforced by the Spectre
simulator; if you violate them, the Spectre simulator issues an error and terminates. You
specify soft limits; if you violate them, the Spectre simulator issues a warning and continues.
Soft limits are used to define reasonable ranges for parameter values and can help find
“unreasonable” values that are likely errors. You can change soft limits, which are defined in
July 2002
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Product Version 5.0