SUBI - Subtraction of Currents

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Model Kind


Model Sub-Kind

Spice Subcircuit

SPICE Prefix


Model Name


SPICE Netlist Template Format

@DESIGNATOR %1 %2 %3 %4 %5 %6 @MODEL

Parameters (definable at component level)



The content of the sub-circuit file (SUBI.ckt) associated with this model is shown below. The formula/equation used to provide this function is declared as part of the netlist-specific entry, under the .SUBCKT line of the file.

*Subtract Currents
.SUBCKT SUBI 1 2 3 4 5 6
VA 1 2 0
VB 3 4 0
BX 6 5 I=I(VA)-I(VB)


Consider the circuit in the image above. With respect to the SUBI component, the entries in the SPICE netlist will be:

*Schematic Netlist:
XM3 NetM3_1 0 NetM3_3 0 OUT 0 SUBI
*Models and Subcircuit:
.SUBCKT SUBI 1 2 3 4 5 6
VA 1 2 0
VB 3 4 0
BX 6 5 I=I(VA)-I(VB)

The effect of the function can be seen in the resultant waveforms obtained by running a transient analysis of the circuit.

In this example, the following analysis parameters on the Transient/Fourier Analysis page of the Analyses Setup dialog have been used:

  • Transient Start Time - set to 0.000
  • Transient Stop Time - set to 50.00m
  • Transient Step Time - set to 200.0u
  • Transient Max Step Time - set to 200.0u
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