Feature: Power supplies
Figure 1: GaN-based-LTspice example circuit featuring EPC2218 FETs with sub-circuit model
To accomplish this, press ‘control’ and right-click on the NMOS symbol. A properties table appears, as shown in Figure 4, and several key attribute changes must now be made. First, the Prefix attribute needs to be changed to x. Tis forces
Figure 2: Vendor GaN model library list example, available for download
LTspice to look locally for a model and the .subkt invocation with the desired name is used instead. Next, change the Value attribute to exactly match the model name directly aſter the .subkt in the first line of the pasted text. Te InstName attribute may optionally be changed to whatever preference the user has (Q, G, etc.); the default is NM, but these are not NMOS FETs once configured to GaN devices. Te final detail to make the model fully operational in the SPICE
file is to ensure the net order convention of the pasted model text matches the order of the standard NMOS device included in LTspice. Te standard NMOS model lists ‘Drainin Gatein Sourcein’ as the convention for the pin number on the NMOS device. Some
Figure 3: Downloaded library files from EPC
the native find function of your system, find the model desired for insertion into the SPICE circuit and copy everything from .subckt to .ends. In the editor, open a .sp SPICE statement box and then paste it into the statement box. It is oſten useful to shrink the size of the pasted text, so it is less obtrusive in the overall draſting space.
Place or edit an existing standard NMOS symbol already in the draſting space to link to the pasted subcircuit model text.
Figure 4: Press control and right-click the standard NMOS device to open the attribute table to use the inserted subcircuit model text
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