I am trying to do some simulations for a circuit that includes a differential amplifier (ADA4945 to be precise). I downloaded its SPICE model and got to work designing a circuit. However, I ran into a problem where the symbol that I use has some pins that are duplicate (e.g. pin 6 and 7 are internally connected). Thus, the symbol exposes 17 pins in total whereas the SPICE model accepts only 14 nodes. This is because the footprint has multiple pins with the same function (i.e. internally connected).
Let’s simplify this with an example:
.Subckt DIFFAMP VinPos VinNeg Vout VsPos VsNeg
Now assume that the KiCad symbol has the following pinout:
Pin | Name |
---|---|
1 | VinPos |
2 | VinNeg |
3 | Vout |
4 | VsPos |
5 |
VsPos (same as pin 4) |
6 | VsNeg |
When I try to run the simulation I get an error as there are too many parameters (6 pins whereas SPICE defines 5 nodes):
Too many parameters for subcircuit type "DIFFAMP" (instance: xxu1)
Taking a look at the generated netlist also reveals that too many pins are passed as parameters:
XU1 +AIN -AIN AOUT +VS +VS -VS DIFFAMP
I tried to edit the alternate node sequence in the SPICE settings for the differential amplifier and added VsPos
twice but still get the same error. My question: How do I ignore pin 5 (the duplicate pin that also maps to VsPos
) without editing the actual SPICE model?