User Guide

Chapter 6 Analog behavioral modeling
150
Placing and specifying ABM
parts
Place and connect ABM parts the same way you place
other parts. After you place an ABM part, you can edit the
instance properties to customize the operational behavior
of the part. This is equivalent to defining an ABM
expression describing how inputs are transformed into
outputs. The following sections describe the rules for
specifying ABM expressions.
Net names and device names in ABM expressions
In ABM expressions, refer to signals by name. This is also
considerably more convenient than having to connect a
wire from a pin on an ABM component to a point carrying
the voltage of interest.
If you used an expression such as V(2), then the referenced
net (2 in this case) is interpreted as the name of a local or
global net. A local net is a labeled wire or bus segment in
a hierarchical schematic, or a labeled offpage connector. A
global net is a labeled wire or bus segment at the top level,
or a global connector.
OrCAD Capture recognizes these constructs in ABM
expressions:
V(<net name>)
V(<
net name>,<net name>)
I(<
vdevice>)
When one of these is recognized, Capture searches for
<net name> or <vdevice> in the net name space or the
device name space, respectively. Names are searched for
first at the hierarchical level of the part being netlisted. If
not found there, then the set of global names is searched.
If the fragment is not found, then a warning is issued but
Capture still outputs the resulting netlist. When a match is
T
h
e name o
f
an inter
f
ace port
d
oes not
extend to any connected nets. To refer to a
signal originating at an interface port,
connect the port to an offpage connector of
the desired name.
Pspug.book Page 150 Wednesday, November 11, 1998 1:14 PM