Converting SPICE Models for use in SIMPLIS - Overview

SPICE models cannot be used directly in the SIMPLIS simulator and, therefore, must be converted through the built-in algorithms. Currently, MOSFETs, Diodes, BJTs, IGBTs, JFETs, and Schottky and Zener diodes are supported.

The process of installing third-party SPICE models requires an association between the electrical definition of the device and the pictorial representation of that device. Although the model provides an electrical description of the device, the model does not specify the schematic symbol nor the category in the model library. Two scenarios are possible:

  • If the device is implemented using a .MODEL control, which always refers to a particular type of device, such as NPN, NMOS, Diode, etc., then SIMetrix can determine the model-library category and the symbol.
  • If the device is implemented as a subcircuit in a .SUBCKT definition, SIMetrix cannot determine the model-library category nor the symbol. For example, a three-terminal regulator and a power MOSFET use identical syntax, but SIMetrix cannot tell the difference from the syntax alone.

To resolve the issue when a device is implemented as a subcircuit in a .SUBCKT definition, the SIMetrix software includes a database of known part numbers with a named schematic symbol, a model-library category and, if relevant, a pin mapping order. The following explains what happens under various conditions:

  • If the part is in the database, the part appears in the model lirary under the correct category with the correct symbol, and no further action is required.
  • If the part is not in the database and has two or three terminals, SIMetrix attempts to determine the type of device by running some simulations on the model.
    • If the simulation is successful, SIMetrix chooses an appropriate schematic symbol without requiring further action.
    • If SIMetrix cannot determine the symbol which describes the model, then you need to provide the associations manually. The first time that you place this part on a schematic, SIMetrix prompts you for the model-library category and the symbol name.

The model-library category and symbol name associations can be embedded in the model definition by editing the model-library file in a text editor. You can add a single line after each .SUBCKT line to identify the model-library category  and the symbol name for the subcircuit definition . For example, the model file included with this topic has the information embedded as follows for the third model that you will install in the next section: 

.SUBCKT example_model_3 1 2 3
*#ASSOC Category=NMOS Symbol=nmos_sub

... model definition lines ... 

.ENDS

Frequently, the automatic association is the most convenient method; however, for associating a large number of models, the embedded association can save time.

Table 1 lists commonly installed models, the corresponding model-library category and symbol name as well as the appropriate entry to add to the model file.

Table 1. Common SPICE Model Types, Categories, and Symbol Names

Model Type Model Library Category Symbol Embedded Association Line
N-Channel MOSFET NMOS NMOS 3 Terminal *#ASSOC Category=NMOS Symbol=nmos_sub
P-Channel MOSFET PMOS PMOS 3 Terminal *#ASSOC Category=PMOS Symbol=pmos_sub
NPN Bipolar Transistor NPN NPN *#ASSOC Category=NPN Symbol=npn
PNP Bipolar Transistor PNP PNP *#ASSOC Category=PNP Symbol=pnp
Diodes Diodes Junction Diode *#ASSOC Category=Diode Symbol=dio
Schottky Diodes Schottky Diodes Schottky *#ASSOC Category="Schottky Diodes" Symbol=diode_schottky
Zener Diodes Zeners Zener *#ASSOC Category=Zeners Symbol=zener_s
N-Channel JFET N-Channel JFET N-Channel JFET *#ASSOC Category="N-Channel JFET" Symbol=njfet
P-Channel JFET P-Channel JFET P-Channel JFET *#ASSOC Category=P-Channel JFET" Symbol=pjfet
N-Channel Enhancement Mode GaN MOSFET NMOS NMOS 3 Terminal *#ASSOC Category=NMOS Symbol=nmos_sub
P-Channel Enhancement Mode GaN MOSFET PMOS PMOS 3 Terminal *#ASSOC Category=PMOS Symbol=pmos_sub
N-Channel Depletion Mode GaN MOSFET N-Channel JFET N-Channel JFET *#ASSOC Category="N-Channel JFET" Symbol=njfet
P-Channel Depletion Mode GaN MOSFET P-Channel JFET P-Channel JFET *#ASSOC Category="P-Channel JFET" Symbol=pjfet
Insulated Gate Bipolar Transistor IGBTs IGBT *#ASSOC Category=IGBTs Symbol=igbt_with_diode