Download - Wolfram Research

2.3 Circuits and Subcircuits 49
Throughout this text, the terms "subcircuit" and "model" shall be used as synonyms because small-signal
device models are effectively implemented as subcircuits composed of circuit primitives like resistors and
controlled sources.
Keeping all netlist and subcircuit components of a circuit together is the task of the Analog Insydes
data structure Circuit (Section 3.1.2), whose content sequence may be any number of netlist and
subcircuit definitions.
Circuit[
Netlist[top-level netlist with subcircuit references],
Model[subcircuit/model definition],
Model[subcircuit/model definition]
]
A Circuit object additionally may contain model parameters and global parameters, see
ModelParameters (Section 3.1.10) and GlobalParameters (Section 3.1.11).
When a Circuit object is defined, it is printed in short notation only. To view the entire circuit
structure use the command DisplayForm.
2.3.2 Defining Subcircuits and Device Models
The Model Object
Let’s start to work with hierarchically structured netlists by learning how to define subcircuits using
the Analog Insydes objects Model (Section 3.2.1) or Subcircuit (Section 3.2.2). This section describes
how to write netlist-based models or subcircuits. Section 2.6.2 shows how to write equation-based
models.
Model and Subcircuit are semantically equivalent symbols. In fact, Subcircuit is just an alias name
for Model. You may want to use both names in a Circuit if you wish to give visual cues as to which
subcircuits represent device models by using the Model directive for these and the Subcircuit object for all
other subcircuits.
The Model object takes several arguments which must all be written in Mathematica’s option syntax
keyword −> value. Four of the arguments must always be present whereas the remaining ones are
optional or have default values. Below, the optional arguments are printed in slanted typewriter
font. For now, we will restrict ourselves to the discussion of the required arguments. The optional
ones will be introduced later in a step-by-step fashion, as this will help you to better understand
why and when they are needed.