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For a simple device, the number of parameters required to model the device is relatively small and the parameters can be easily blended with the device statement. For example, the resistance, the inductance, and the capacitance of a linear resistor, inductor, and capacitor, respectively, are all defined in the device statements. For devices such as simple switches, piecewise-linear elements, and simple logic gates, a large number of parameters is needed to describe the device performance. In such cases, the model statements provide a convenient and organized way to define the model parameters.
There are two additional advantages in using the model statements. Quite often, several devices in the system being studied may have the same model parameters. In such cases, one single model statement can provide the model parameters for all of the devices of the same type. Another benefit of this arrangement is when several devices are described by the same device model, then the model characteristics of all of these devices can be altered at the same location by modifying the model statement which is common to all.
A typical model statement can be represented by the following example statement:
| .MODEL mname mtype param param ... |
where
| .MODEL | is the six-character keyword ".MODEL" |
| mname | is a legal model name as explained in Model Names and Subcircuit Names. A model name must be unique within a general circuit. If a name is used as a model name in a general circuit, it cannot be used as a subcircuit name in the same general circuit and vice versa. |
| mtype | is a keyword which stands for one of the model types supported by SIMPLIS. The list of device models recognized by SIMPLIS is shown in the table below. |
| param | is a parameter assignment in the form illustrated in Parameter Assignments. |
Device Model Types Used by SIMPLIS
| Model Type | Description |
|---|---|
| VCSW | Voltage-Controlled Simple Switch |
| ICSW | Current-Controlled Simple Switch |
| VCQPOS VCQNEG | Voltage-Controlled Simple Transistor Switch |
| ICQPOS ICQNEG | Current-Controlled Simple Transistor Switch |
| VPWLR IPWLR | Piecewise-Linear Resistor |
| PWLL | Piecewise-Linear Inductor |
| PWLC | Piecewise-Linear Capacitor |
| INV | Simple Logic Gate, Inverter |
| COMP | Simple Logic Gate, Comparator |
| XOR | Simple Logic Gate, Exclusive OR |
| ORk | Simple Logic Gate, k-input OR, where k is an integer, 2 $\leq$ k $\leq$ 9 |
| NORk | Simple Logic Gate, k-input NOR, where k is an integer, 2 $\leq$ k $\leq$ 9 |
| ANDk | Simple Logic Gate, k-input AND, where k is an integer, 2 $\leq$ k $\leq$ 9 |
| NANDk | Simple Logic Gate, k-input NAND, where k is an integer, 2 $\leq$ k $\leq$ 9 |
| SRFF | Simple Logic Gate, Set-Reset Flip Flop |
| CLK_SRFF | Clocked Logic Gate, Clocked Set-Reset Flip Flop |
| CLK_JKFF | Clocked Logic Gate, Clocked JK Flip Flop |
| CLK_DFF | Clocked Logic Gate, Clocked D Flip Flop |
| CLK_TFF | Clocked Logic Gate, Clocked Toggle Flip Flop |
| LATCH | Latch |
| .MODEL S1 VCSW TH=2 HYSTWD=2U RON=10m |
| + ROFF=10MEG LOGIC=POS |
| .MODEL S1 VCSW RON=10m ROFF=10MEG |
| + TH=2 HYSTWD=2U LOGIC=POS |
Parameter assignments in SIMPLIS do not assume default values. Therefore, each required parameter must be assigned a proper value in the .MODEL statement.
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