Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(1)

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“A Concise Model for Static Induction Transistor IV Characteristics” - Michael Rothacher
In his publication, a equation is given to find model for simulation:

Id=K*(Vg+Vct+N*LN(Vd)+Vd/Mu)^X

.SUBCKT TFH51S D G S
+ PARAMS: K=0.157 MU=7.3 N=2.24 X=1.51 VCT=0.0
B1 D S I=K*PWR(URAMP((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU))),X)
.ENDS TFH51S

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(2)

It is very good tool to make SIT model sim parameters like shown in his paper.
But it takes some effort to find a group of parameter to a given SIT

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(3)

Step 1: A picture of a tracer curve of a SIT

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(4)

Step 2 Crop the area interested (for instance, 30V and 5A), and save it as any picture

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(5)

Step 3 Open an Excel worksheet, insert Scatter (X,Y), format Y axis Min 0, max 5, Major 0.5, Minor 0.1, format X axis Min 0, Max 30, Major 5, Minor 1, format major gridlines, add minor gridlines, format chart area No Fill, it becomes transparent

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(6)

Step 4 Insert or copy the curve picture into the sheet and send it back. Overlay the X,Y plot on top of it, drag the Conner of the tracer curve to match both X and Y axes perfectly.

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(7)

Step 5 Read Id value at every 1 Vds for each Vgs, using the picture created in Step 4. The major and minor grid lines help to do more easily and accurately. Input the data to the sheet as shown in photo.

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(8)

Step 6 Repeat Step 3 again but with the data. Make the exact size like before. Overlay the plot on top of the tracer curve. Now it the time to check if the value points match the curve. If not, modify the data to make the points fit the curves exactly.

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(9)

Step 7 make a new worksheet like this, Copy the data in Step 5 into the sheet for each Vgs. Start from Cell A10, Vgs, B10 Vds, C10 Id

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(10)

Step 8 Equations in Cell D10 (Id_Fit), E10 (Residual), F10 (Square Residual) and H2 (Sum of all Square Residual)
a. Copy the initial values into Results
b. In D10, input the equation exactly like this
=IF(A10+$C$2+$D$2*LN(B10)+B10/$E$2<0, 0, $B$2*(A10+$C$2+$D$2*LN(B10)+B10/$E$2)^$F$2)
c. In E10, input the equation exactly like this
=C10-D10
d. In F10, input the equation exactly like this
=E10^2
e. Mark D10, E10 and F10, copy, then Paste only function in all the cells below, Now all calculated values should be shown
f. Equation in Cell H2
=SUM(F10:F1000)

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(11)

Step 9 Activate Microsoft Excel Solver Add-in (by default is not added in yet)
Pull down Menu: File -> Options -> Add-ins: Select or Highlight: Solver Add-in
Then: Manage: Excel Add-in , Go….., Check: Solver Add-in, OK

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(12)

Step 10 Using the Add-in

Pull down Menu: Data, click Solver, fill the fields needed, then: Solve

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(13)

Step 11 Pop up and OK. Repeat Step 10 few times until the results not change anymore.
Open model, and change the parameters and save.

.SUBCKT TFH51S_Min D G S
+ PARAMS: K=1.91 MU=25.86 N=0.533 X=1.67 VCT=1.67
B1 D S I=K*PWR(URAMP((V(G,S)+VCT)+(N*LN(V(D,S))+(V(D,S)/MU))),X)
.ENDS TFH51S_Min

 

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Using Microsoft Excel Solver to Find a SIT Sim Model Parameters(14)

Step 12 Test and Verification

Find few random Vgs, Vds and Ids points in the tracer curve, and test it.


Enjoy!

 

[Zen Mod]

yikes!

🙂

 

[AlexRivera]

 

[Michael Rothacher]

Nice tutorial! Here's a little video I did on Excel a few years back in case its of use. 🙂

VLOG #1: Curve Tracer, Big VFET, SIT Modelling, Ironamp - YouTube

 

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Thank you very much! That's all your excellent work.

 

[Nelson Pass]

Most excellent piece.

 

[GnuB]

Wow!
Very cool!!
Thanks!!