User`s guide

6
-
22 Analo
g
Behavioral Modelin
g
requirements. Each of these parts has a set of four expression
building block attributes of the form:
EXP n
where n = 1, 2, 3, or 4.
During netlist generation, the complete expression is formed by
concatenating the building block expressions in numeric order,
thus defining the transfer function. Hence, the first expression
fragment should be assigned to the EXP1 attribute, the second
fragment to EXP2, and so on.
Expression attributes can be defined using a combination of
arithmetic operators and input designators. You may use any of
the standard PSpice A/D arithmetic operators (see Table 3-1 on
page 3-17) within an expression statement. You may also use
the EXPn attributes as variables to represent nets or constants.
The following examples illustrate a variety of ABM expression
part applications.
Example 1
Suppose you want to set an output voltage on net 4 to 5 volts
times the square root of the voltage between nets 3 and 2. You
could use an ABM2 part (which takes two inputs and provides a
voltage output) to define a part like the one shown in Figure 6-9.
Table 6-3
ABM Expression Parts
Device Inputs Output
ABM none V
ABM1 1 V
ABM2 2 V
ABM3 3 V
ABM/I none I
ABM1/I 1 I
ABM2/I 2 I
ABM3/I 3 I
Fi
g
ure 6-9
ABM Expression
Part Example 1