User Guide

Components of a Design
29
Components of a Design
A schematic consists of:
• symbols
• attributes
• wires
• buses
• text items
Schematics can have either a flat or hierarchical structure,
depending on the way you decide to implement your
design.
Parts
Parts are electrical devices that make up a circuit, such as:
• resistors
• operational amplifiers
• diodes
• voltage sources
• digital gates
The graphical representation of a part is a symbol.
Symbols are stored in symbol libraries.
PSpice Sc
h
ematics uses two
b
asic types o
f
parts: primitive and hierarchical.
Primitive parts are at the lowest level and
explicitly contain all of the information
required by the netlister. Most symbols in
the symbol libraries are primitive parts.
Hierarchical parts have the same
appearance as primitive parts. The
difference is that hierarchical parts
represent one or more levels of schematics
and primitive parts do not.
A hierarchical part is modified by pushing
into it from within the schematic editor or
symbol editor and editing the associated
schematic.
A primitive part is modified by editing its
graphics, pins, and attributes.