Uses of the Comparator Macromodel

You can use the comparator macromodel by doing the following:

• Defining the common specification sheet values, available in most semiconductor product catalogs.
• Placing the comparator macromodel symbol in your schematic.
• Defining the CDF parameter values and by using default values for parameters that you do not set.

Electrical effects are modeled accurately by this macromodel. However, such a simple circuit might not work as a comprehensive model. The comparator macromodel cannot do the following:

• Model specifications that are not defined as macromodel parameters
• Model high frequency response
  The behavior of the comparator at a frequency higher than 1/(4 × t ds) is not expected to match the circuit measurements. The capacitor of the single time constant circuit is not fully charged. The delay time might not be realistic.
• Vary delay time according to the input overdrive voltage
• Model hysteresis effects.

Setup of the Comparator Macromodel into a design

The following figure shows a comparator macromodel symbol.

For proper operation of the macromodel, you need to connect the following three I/O pins:

IN	Positive input terminal
INN	Negative input terminal
OUT	Output terminal

Comparator Macromodel Parameters

There are 12 parameters you can use to describe the behavior of the comparator macromodel.

Property	Typical Value	Description
ibias	200n	Input bias current
vos	0	Input offset voltage
ios	10n	Input offset current
rin	1meg	Input resistance
cin	1p	Input capacitance
voh	5	Positive output voltage swing
vol	0	Negative output voltage swing
vis	2m	Overdrive voltage for small-signal transient response test
trs	20n	Small-signal rising and falling time
tds	50n	Small-signal delay time
gol	100k	Open loop gain
ro	200	Output resistance

Related Topics

Introduction to Functional Block Library

Comparator Symbol

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