DIY Audio Lab

SIT Curve Fitter

Rothacher model parameter extraction using Nelder–Mead optimization

Data Import

Export one from the Characteristic Curve Digitizer.
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Rothacher SIT Model

Id = K · (Vg + Vct + N·ln(Vd) + Vd/μ)X

“A Concise Model for Static Induction Transistor IV Characteristics”, Michael Rothacher, Linear Audio Vol 6.

Gain coefficient
Amplification factor
Log Vd coefficient
Exponent
Threshold offset

Optimizer Settings

Fit Results

Run curve fit to see results...

IV Curve Plot

SPICE Subcircuit Model

Fit the model to generate SPICE output...