Documentation

BJT model from Datasheet

 

BJT bipolar transistors require a certain number of parameters to get a good model.The syntax for this model is:

 .model ModelNameNPN (par1=a par2=b.........parn=x)

for PNP case:

.model ModelNamePNP (par1=a par2=b.........parn=x)

where par1 par2.......parn are the parameters that allow to model equations of the BJT.

The main parameters for a reasonable modeling of the behavior of the component are summarized in the following table:

 

Parameters

 

Description

Units

Default

IS

Transport saturation current

A

1e-16

XTI

IS temperature effect exponent

no unit dimension

3.0

EG

Bandgap voltage (barrier height)

eV

1.11

VAF

Forward Early voltage

V

Infinite

BF

Ideal maximum forward beta

no unit dimension

100

ISE

Base-emitter leakage saturation current

A

0

NE

Base-emitter leakage emission coefficient

no unit dimension

1.5

IKF

Corner for forward-beta high-current roll-off

A

Infinite

NK

High-current roll-off coefficient

no unit dimension

0.5

XTB

Forward and reverse beta temperature coefficient

no unit dimension

0

BR

Ideal maximum reverse beta

no unit dimension

1.0

ISC

Base-collector leakage saturation current

A

0

NC

Base-collector leakage emission coefficient

no unit dimension

2.0

IKR

Corner for reverse-beta high-current roll-off

A

Infinite

RC

Collector ohmic resistance

Ohm

0

CJC

Base-collector zero-bias p-n capacitance

F

0

MJC

Base-collector p-n grading factor

no unit dimension

0.33

VJC

 

V

0.75

FC

Forward-bias depletion capacitor coefficient

no unit dimension

0.5

CJE

Base-emitter zero-bias p-n capacitance

F

0

MJE

Base-emitter p-n grading factor

no unit dimension

0.33

VJE

Base-emitter built-in potential

V

0.75

TR

Ideal reverse transit time

s

1e-8

TF

Ideal forward transit time

s

0

ITF

Transit time dependency on Ic

A

0

XTF

Transit time bias dependence coefficient

no unit dimension

0

VTF

Transit time dependency on Vbc

V

Infinite

RB

Zero-bias (maximum) base resistance

Ohm

0

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